UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT ~~PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934~~

~~Date~~ Pursuant ofto ~~Report~~Section 13 or 15(~~Date~~d) of ~~earliest~~the ~~event~~Securities ~~reported):~~Exchange ~~July 2,~~Act ~~2006~~of 1934

~~SUMMIT~~ Date ~~BANCSHARES~~of Report: July 17, ~~INC.~~ 2006

(Exact name of registrant as specified in its charter)

SUMMIT BANCSHARES, INC.

(Exact name of registrant as specified in its charter)

Texas	0-11986	75-1694807

(State of Incorporation)	(Commission File Number)	(I.R.S. Employer ID No.)

3880 Hulen Street, Fort Worth, Texas 76107

(Address of principal executive offices)

(817) 336-6817

(Registrant’s telephone number, including area code)

N/A

(Former name or former address, if changed since last report.)

~~Texas~~ Check ~~(State~~the orappropriate ~~other~~box ~~jurisdiction~~below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of ~~incorporation~~the orregistrant ~~organization)~~under ~~0-11986~~any ~~(Commission~~of ~~File~~the ~~Number)~~following ~~75-1694807~~provisions (~~I.R.S.~~see ~~Employer~~General ~~Identification~~Instructions NoA.2. below):

~~3880~~o ~~Hulen~~Written ~~Fort~~communications ~~Worth,~~pursuant ~~Texas~~to Rule 425 under the Securities Act (~~Address~~17 ofCFR ~~principal~~230.425) ~~executive~~o ~~offices~~Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ~~76107~~o Pre-commencement communications pursuant to Rule 14d-2(~~Zip~~b) ~~Code~~under the Exchange Act (17 CFR 240.14d-2(b)) o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

~~Registrant’s~~ ITEM ~~telephone~~2.02. Results ~~number,~~of ~~including~~Operations ~~area~~and ~~code:~~Financial ~~(817) 336-6817~~Condition.

~~Check~~ On ~~the~~July ~~appropriate~~17, ~~box~~2006, ~~below~~Summit ifBancshares, ~~the~~Inc. ~~Form~~(“Summit ~~8-K~~Bancshares”) ~~filing~~issued isa ~~intended~~press torelease ~~simultaneously~~announcing ~~satisfy~~ its earnings for the ~~filing~~second ~~obligation~~quarter of ~~the~~2006. A ~~registrant~~copy ~~under~~of ~~any~~Summit ofBancshares’ ~~the~~press ~~following~~release ~~provisions~~is ~~(see~~attached ~~General Instruction~~hereto Aas Exhibit 99.1. The press release is incorporated by reference into this Item 2.02 ~~below):~~ and the foregoing description of the press release is qualified in its entirety by reference to this exhibit.

o ITEM ~~Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230~~7.~~425) þ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240~~01.~~14a-12)~~ REGULATION oFD Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))DISCLOSURE

See Item ~~1.01~~ ~~Entry into a Material Definitive Agreement~~2. 02

~~Amendment~~ITEM to9.01. Financial ~~Rights~~Statements ~~Agreement~~ and Exhibits

On July 2, 2006, Summit Bancshares, Inc., a Texas corporation (“Summit”), and Summit Bank, National Association, a national banking association (the “Bank”), as Rights Agent, entered into Amendment No. 2 to Rights Agreement (the “Amendment”), which amends the Rights Agreement dated as of April 16, 1990, as amended, between Summit and Summit Bancservices, Inc. as Rights Agent. The purpose of the Amendment, among other things, is to clarify that Cullen/Frost (as defined below) is not an Acquiring Person for purposes of the Rights Agreement and that the entry into the Agreement (as defined below), or any transaction contemplated thereby, would not be deemed to be an Acquisition Event or Section 13 Event for purposes of the Rights Agreement. The Amendment also provides that the Rights Agreement will be terminated immediately prior to completion of the merger of Summit with and into Cullen/Frost as described below, if such merger occurs prior to the other events of termination.

	(c)	Exhibits

		The following exhibits are furnished with this Form 8-K.

		99.1 Press Release dated July 17, 2006

~~The foregoing summary of the Amendment is not complete and is qualified in its entirety by~~ ~~reference to the complete text of such document, which is filed as Exhibit 4.1 to this Current Report on Form 8-K and which is incorporated herein by reference.~~ SIGNATURE

~~Entry~~ Pursuant ~~into~~to ~~Agreement~~the ~~and~~requirements ~~Plan~~of the Securities Exchange Act of ~~Merger~~ 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

On July 2, 2006, Summit and Cullen/Frost Bankers, Inc., a Texas corporation (“Cullen/Frost”), entered into an Agreement and Plan of Merger (the “Agreement”) pursuant to which Summit will merge with and into Cullen/Frost. Under the terms of the Agreement, Summit shareholders will have the right, subject to pro-ration, to elect to receive cash, shares of Cullen/Frost common stock or a combination thereof having a value equal to $11.50 plus 0.2933 Cullen/Frost shares. The total consideration consists of approximately $143.4 million in cash and approximately 3.84 million shares of Cullen/Frost common stock (assuming the treasury stock method of accounting for options before giving effect to any exercises in outstanding options). The transaction is subject to customary closing conditions, including the receipt of regulatory approvals and approval of the shareholders of Summit. The merger is currently expected to be completed in the fourth quarter of 2006, although delays could occur.

	SUMMIT BANCSHARES, INC.

	By:	/s/ Bob G. Scott

DATE: July 17, 2006		Bob G. Scott, Chief Operating Officer

The joint news release announcing the transaction is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The foregoing summary of the Agreement is not complete and is qualified in its entirety by reference to the complete text of such document, which is filed as Exhibit 2.1 to this Current Report on Form 8-K and which is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

Exhibit
Number		Description of Exhibit
2.1		Agreement and Plan of Merger by and between Summit Bancshares, Inc. and Cullen/Frost Bankers, Inc. dated as of July 2, 2006
4.1		Amendment No. 2 to the Rights Agreement by and between Summit Bancshares, Inc. and Summit Bank, National Association, as Rights Agent, effective as of July 2, 2006
99.1		Joint News Release issued by Cullen/Frost Bankers, Inc. and Summit Bancshares, Inc. dated July 3, 2006

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	SUMMIT BANCSHARES, INC. (Registrant)
Dated: July 3, 2006	By:	/s/ Bob G. Scott
		Bob G. Scott
		Executive Vice President and Chief Operating Officer

EXHIBIT INDEX

Exhibit
Exhibit Number		Description of Exhibit
Number		Description of Exhibit
99.1		Press Release dated July 17, 2006
2.1		Agreement and Plan of Merger by and between Summit Bancshares, Inc. and Cullen/Frost Bankers, Inc. dated as of July 2, 2006
4.1		Amendment No. 2 to the Rights Agreement by and between Summit Bancshares, Inc. and Summit Bank, National Association, as Rights Agent, effective as of July 2, 2006
99.1		Joint News Release issued by Summit Bancshares, Inc. and Cullen/Frost Bankers, Inc. dated July 3, 2006

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