SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D

                               (Amendment No. 4)

                   Under the Securities Exchange Act of 1934*

                            Carrizo Oil & Gas, Inc.
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                                (Name of Issuer)

                     Common Stock, par value $.01 per share
- ------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                  144577 10 3
- ------------------------------------------------------------------------------
                                 (CUSIP Number)

                               Paul B. Loyd, Jr.
                            Carrizo Oil & Gas, Inc.
                        14701 St. Mary's Lane, Suite 800
                              Houston, Texas 77079
                                 (281) 496-1352
- ------------------------------------------------------------------------------
            (Name, Address and Telephone Number of Person Authorized
                     to Receive Notices and Communications)

                               September 30, 2003
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            (Date of Event which Requires Filing of this Statement)

If the filing person has previously  filed a statement on Schedule 13G to report
the  acquisition  that is the subject of this  Schedule  13D, and is filing this
schedule  because  of  240.13d-1(e),  240.13d-1(f)  or  240.13d-1(g),  check the
following box [].

Note:  Schedules  filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 13d-7 for other parties
to whom copies are to be sent.

*The remainder of this cover page should be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for  any  subsequent   amendment   containing   information  which  would  alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).

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CUSIP No. 144577 10 3
- ------------------------------------------------------------------------------
1    NAME OF REPORTING PERSON
     S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

     Paul B. Loyd, Jr.

- ------------------------------------------------------------------------------
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*                 (a) [ ]

                                                                       (b) [X]

- ------------------------------------------------------------------------------
3    SEC USE ONLY


- ------------------------------------------------------------------------------
4    SOURCE OF FUNDS*

     00

- ------------------------------------------------------------------------------
5    CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
     ITEMS 2(d) OR 2(e)                                                    [ ]

- ------------------------------------------------------------------------------
6    CITIZENSHIP OR PLACE OF ORGANIZATION

     United States of America

- ------------------------------------------------------------------------------
                 7    SOLE VOTING POWER

                      1,355,299 Shares (92,006 of which are issuable upon the
                      exercise of a warrant and 20,000 of which are issuable
                      upon the exercise of certain options)

                 ---------------------------------------------------------------
                 8    SHARED VOTING POWER
  NUMBER OF
   SHARES             0 Shares
BENEFICIALLY
  OWNED BY       ---------------------------------------------------------------
    EACH         9    SOLE DISPOSITIVE POWER
  REPORTING
    PERSON            1,355,299 Shares (92,006 of which are issuable upon the
     WITH             exercise of a warrant and 20,000 of which are issuable
                      upon the exercise of certain options)

                 ---------------------------------------------------------------
                 10   SHARED DISPOSITIVE POWER

                      0 Shares

- ------------------------------------------------------------------------------
11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     1,355,299 Shares

- ------------------------------------------------------------------------------
12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [X]


- ------------------------------------------------------------------------------
13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

     9.4%

- ------------------------------------------------------------------------------
14   TYPE OF REPORTING PERSON*

     IN

- ------------------------------------------------------------------------------


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INTRODUCTORY NOTE.

               This  Amendment  No. 4 to  Schedule  13D is being filed on behalf
Paul B. Loyd, Jr. ("Mr.  Loyd") to supplement  certain  information set forth in
the  Schedule  13D relating to  securities  of Carrizo Oil & Gas,  Inc., a Texas
corporation (the "Company"), originally filed by Mr. Loyd on August 21, 1997 and
amended by Amendment No. 1 dated January 8, 1998, Amendment No. 2 dated December
15,  1999 and  Amendment  No. 3 dated  February  20,  2002 (as so  amended,  the
"Original  Statement"),  with  respect to the Common  Stock,  par value $.01 per
share (the "Common Stock"),  of the Company.  Unless otherwise  indicated,  each
capitalized  term used but not defined herein shall have the meaning assigned to
such term in the Original Statement.

Item 4.        Purpose of Transaction

               On December 30, 2002,  Mr. Loyd donated  77,175  shares of Common
Stock as a charitable gift.

               On September 24, 2003,  Mr. Loyd sold on the Nasdaq Stock Market:
3,100 shares of Common Stock for an aggregate  sales price of $22,022 ($7.10 per
share, including commissions;  $7.03 per share, excluding  commissions);  40,900
shares of Common  Stock for an  aggregate  sales  price of  $296,525  ($7.25 per
share, including commissions;  $7.18 per share, excluding  commissions);  58,000
shares of Common  Stock for an  aggregate  sales  price of  $414,700  ($7.15 per
share,  including  commissions;  $7.08 per share,  excluding  commissions);  and
10,000 shares of Common Stock for an aggregate sales price of $72,700 ($7.27 per
share, including commissions; $7.20 per share, excluding commissions).

               On September 25, 2003,  Mr. Loyd sold on the Nasdaq Stock Market:
5,500 shares of Common Stock for an aggregate  sales price of $38,500 ($7.00 per
share, including commissions;  $6.85 per share,  excluding  commissions);  1,077
shares of Common  Stock for an  aggregate  sales price of  $7,614.39  ($7.07 per
share, including commissions;  $6.92 per share, excluding commissions); 2 shares
of Common  Stock  for an  aggregate  sales  price of $14.20  ($7.10  per  share,
including commissions;  $6.95 per share, excluding  commissions);  300 shares of
Common Stock for an aggregate sales price of $2,205 ($7.35 per share,  including
commissions;  $7.28 per share, excluding  commissions);  12,900 shares of Common
Stock for an  aggregate  sales  price of $94,170  ($7.30  per  share,  including
commissions;  $7.23 per share,  excluding  commissions);  3,000 shares of Common
Stock for an  aggregate  sales  price of $21,930  ($7.31  per  share,  including
commissions;  $7.23 per share,  excluding  commissions);  1,500 shares of Common
Stock for an  aggregate  sales  price of $10,920  ($7.28  per  share,  including
commissions;  $7.21 per share,  excluding  commissions);  9,500 shares of Common
Stock for an  aggregate  sales  price of $68,970  ($7.26  per  share,  including
commissions;  $7.19 per share, excluding  commissions);  18,900 shares of Common
Stock for an  aggregate  sales  price of  $137,025  ($7.25 per share,  including
commissions;  $7.18 per share,  excluding  commissions) and 600 shares of Common
Stock  for an  aggregate  sales  price of $4,338  ($7.23  per  share,  including
commissions; $7.16 per share, excluding commissions).

               On September 30, 2003,  Mr. Loyd sold on the Nasdaq Stock Market:
9,100 shares of Common Stock for an aggregate  sales price of $64,610 ($7.10 per
share, including commissions;  $7.03 per share,  excluding  commissions);  2,131
shares of Common Stock for an

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aggregate  sales price of $15,236.65  ($7.15 per share,  including  commissions;
$7.08 per share,  excluding  commissions);  1,500  shares of Common Stock for an
aggregate sales price of $10,785 ($7.19 per share, including commissions;  $7.12
per share, excluding commissions); 2,000 shares of Common Stock for an aggregate
sales price of $14,280 ($7.14 per share, including commissions; $7.07 per share,
excluding commissions);  and 1,000 shares of Common Stock for an aggregate sales
price of $7,120  ($7.12  per  share,  including  commissions;  $7.05 per  share,
excluding commissions).

               On October 1, 2003,  Mr.  Loyd sold on the Nasdaq  Stock  Market:
1,000 shares of Common Stock for an aggregate  sales price of $7,070  ($7.07 per
share, including commissions;  $7.00 per share,  excluding  commissions);  2,600
shares of Common Stock for an aggregate sales price of $18,460 ($7.10 per share,
including commissions; $7.03 per share, excluding commissions); and 1,430 shares
of Common Stock for an  aggregate  sales price of  $10,253.10  ($7.17 per share,
including commissions; $7.10 per share, excluding commissions).

               On October 9, 2003, Mr. Loyd sold on the Nasdaq Stock Market: 400
shares of Common Stock for an aggregate  sales price of $2,864  ($7.16 per share
including commissions;  $7.09 per share excluding commissions);  6,460 shares of
Common Stock for an aggregate  sales price of $45,866 ($7.10 per share including
commissions;  $7.03 per share excluding commissions); 600 shares of Common Stock
for an aggregate sales price of $4,272 ($7.12 per share  including  commissions;
$7.05 per share  excluding  commissions);  27,000  shares of Common Stock for an
aggregate sales price of $193,050 ($7.15 per share including commissions;  $7.08
per share excluding commissions);  2,600 shares of Common Stock for an aggregate
sales price of $18,408 ($7.08 per share including  commissions;  $7.01 per share
excluding  commissions);  1,500 shares of Common  Stock for an  aggregate  sales
price of  $10,770  ($7.18  per  share  including  commissions;  $7.11  per share
excluding  commissions);  4,600 shares of Common  Stock for an  aggregate  sales
price of  $33,028  ($7.20  per  share  including  commissions;  $7.13  per share
excluding  commissions);  and 800 shares of Common Stock for an aggregate  sales
price of  $5,672  ($7.09  per  share  including  commissions;  $7.01  per  share
excluding commissions).

Item 5.         Interest in Securities of the Issuer

               As of November 17, 2003, Mr. Loyd  beneficially owns an aggregate
of 1,355,299 shares of Common Stock (approximately 9.4% of the 14,485,557 shares
deemed to be  outstanding  as of September  30, 2003  (consisting  of 14,373,551
shares of Common  Stock,  92,006  warrants to purchase  Common  Stock and 20,000
options that are exercisable  within 60 days)).  Such ownership does not include
any  beneficial  ownership that may be attributed to Mr. Loyd as a result of his
being a party to  certain  Shareholders  Agreements  described  in the  Original
Statement.

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               After  reasonable  inquiry and to the best of his  knowledge  and
belief,  the  undersigned  certifies  that  the  information  set  forth in this
statement is true, complete and correct.

Date:  November 30, 2003.

                                                /s/ Paul B. Loyd, Jr.
                                                --------------------------------
                                                Paul B. Loyd, Jr.

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