Exhibit 5

PORTER WRIGHT MORRIS & ARTHUR LLP

41 South High Street

Columbus, Ohio 43215-6194

Telephone: 614/227-2000

Facsimile: 614/227-2100

August 15, 2012

Huntington Bancshares Incorporated

Huntington Center

41 S. High St.

Columbus, Ohio 43287

Huntington Bancshares Incorporated 2012 Long-Term Incentive Plan (the “Plan”)

Gentlemen:

We have acted as counsel for Huntington Bancshares Incorporated, a Maryland corporation (“Huntington”), in connection with the Registration Statement on Form S-8 (the “Registration Statement”), filed by Huntington with the Securities and Exchange Commission under the Securities Act of 1933, as amended, with respect to the registration of 51,000,000 shares of Huntington common stock, $0.0 par value (the “Shares”), to be issued under the Plan.

In connection with this opinion, we have examined such corporate records, documents, and other instruments of the registrant as we have deemed necessary.

Based on the foregoing, we are of the opinion that the Shares will, when issued and paid for in accordance with the provisions of the Plan, be legally issued, fully paid and nonassessable, and entitled to the benefits of the Plan.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement.

Very truly yours,

/s/ PORTER WRIGHT MORRIS & ARTHUR LLP

PORTER WRIGHT MORRIS & ARTHUR LLP