EXHIBIT 5.1

CALLISTER NEBEKER & MCCULLOUGH

A PROFESSIONAL CORPORATION

ATTORNEYS AT LAW

ZIONS BANK BUILDING SUITE 900

10 EAST SOUTH TEMPLE

SALT LAKE CITY, UTAH 84133

TELEPHONE 801-530-7300

FAX 801-364-9127

August 18, 2010

Zions Bancorporation

One South Main, 15^th Floor

Salt Lake City, Utah 84111

Ladies and Gentlemen:

We have acted as Utah counsel to Zions Bancorporation, a Utah corporation (the “Company”), in connection with the Registration Statement on Form S-3 (File No. 333-158319) of the Company filed on March 31, 2009 with the Securities and Exchange Commission (the “Commission”), as amended at the time each part of such registration statement became effective (the “Registration Statement”), and the Prospectus Supplement, dated August 18, 2010 (the “Prospectus Supplement”), of the Company filed with the Commission, relating to the issuance and sale by the Company of shares of the Company’s common stock, no par value per share (the “Shares”), having an aggregate offering price of up to $200,000,000, that are being issued and sold in accordance with the Equity Distribution Agreement, dated as of August 18, 2010, between the Company and Goldman, Sachs & Co. (the “GS Distribution Agreement”), and the Equity Distribution Agreement, dated as of August 18, 2010 between the Company and Deutsche Bank Securities, Inc. (collectively with the GS Distribution Agreement, the “Distribution Agreements”).

This opinion is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Act.

In connection with this representation, we have examined the originals, or copies identified to our satisfaction, of such minutes, agreements, corporate records and filings and other documents necessary to or appropriate for our opinion contained in this letter (the “Transaction Documents”). In our examination of the Transaction Documents, we have assumed the genuineness of all signatures that exist on those documents and have assumed the authenticity and regularity of each of the Transaction Documents submitted to us. We have also relied as to certain matters of fact upon representations made to us by public officials, officers and agents of the Company, and other sources we believe to be responsible. We have also assumed that all relevant corporate actions heretofore taken by the Company will remain in full force and effect and, after the date hereof, no such corporate action shall have been amended or rescinded and no action inconsistent or in conflict with any such corporate action shall have been taken by or on behalf of the Company.

Based upon and in reliance on and subject to the foregoing, and subject to the assumptions, qualifications and limitations set forth herein, it is our opinion that the Shares have been duly authorized, and when issued, delivered and paid for in accordance with the terms of the Distribution Agreements, the Shares will be validly issued and will be fully paid and non-assessable.

Zions Bancorporation

August 18, 2010

Page 2

Although we have reviewed the Transaction Documents, and have made such inquiries as we deem appropriate under the circumstances, we have not verified independently the existence or absence of all of the facts set forth in each such Transaction Documents.

Our opinion, as set forth herein, is subject to the following further qualifications:

(A) This opinion speaks only as of its date and you understand that this firm has no obligation to advise you of any changes of law or fact that occur after the date of this opinion, even if the change may affect the legal analysis, a legal conclusion or any informational confirmation in this opinion.

(B) Members of our firm are admitted to the Bar in the State of Utah. This opinion is limited to the federal laws of the United States and the laws of the States of Utah, and we have not been asked to address nor have we addressed or expressed an opinion on the laws of any other jurisdiction.

We hereby consent to the filing of this opinion as an exhibit to the Company’s Current Report on Form 8-K filed on August 18, 2010 and incorporated by reference in the Registration Statement, and to the reference to us under the heading “Validity of Securities” in the Prospectus Supplement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act.