Exhibit 5.1

March 20, 2017

Board of Directors

QTS Realty Trust, Inc.

12851 Foster Street

Overland Park, KS 66213

Ladies and Gentlemen:

We are acting as counsel to QTS Realty Trust, Inc., a Maryland corporation (the “Company”), in connection with the public offering of up to $300,000,000 aggregate gross sales price of the Company’s Class A common stock, par value $0.01 per share (the “Shares”), all of which are to be offered and sold by the Company from time to time in accordance with the terms of the Equity Distribution Agreements, each dated March 20, 2017, among the Company, QualityTech, LP (the “Operating Partnership”) and each of the persons named on Schedule 1 attached hereto, respectively (the “Agreements”).  The offering of the Shares by the Company is being made pursuant to a prospectus supplement dated March 20, 2017 and the accompanying base prospectus dated March 28, 2016 (such documents, collectively, the “Prospectus”) that form part of the Company’s effective registration statement on Form S-3 (File No. 333-210425) (the “Registration Statement”). This opinion letter is furnished to you at your request to enable you to fulfill the requirements of Item 601(b)(5) of Regulation S-K, 17 C.F.R. § 229.601(b)(5), in connection with the Registration Statement.

For purposes of this opinion letter, we have examined copies of such agreements, instruments and documents as we have deemed an appropriate basis on which to render the opinions hereinafter expressed. In our examination of the aforesaid documents, we have assumed the genuineness of all signatures, the legal capacity of all natural persons, the accuracy and completeness of all documents submitted to us, the authenticity of all original documents, and the conformity to authentic original documents of all documents submitted to us as copies (including pdfs).  We also have assumed that the Shares will not be issued in violation of the ownership limit contained in the Company’s Articles of Amendment and Restatement.  As to all matters of fact, we have relied on the representations and statements of fact made in the documents so reviewed, and we have not independently established the facts so relied on.  This opinion letter is given, and all statements herein are made, in the context of the foregoing.

This opinion letter is based as to matters of law solely on the applicable provisions of Maryland General Corporation Law, as amended.  We express no opinion herein as to any other laws, statutes, ordinances, rules or regulations.

Based upon, subject to and limited by the foregoing, we are of the opinion that following (i) execution and delivery by the Company and the Operating Partnership of the Agreements, (ii) authorization by the Company’s Board of Directors, or authorization by a duly authorized pricing committee thereof, within the limitations established by resolutions duly adopted by the Company’s Board of Directors and duly authorized pricing committee thereof, of the terms pursuant to which the Shares may be sold pursuant to the Agreements, (iii) authorization by a duly authorized executive officer, designated by the pricing committee to approve placement notices under the Agreements, of the terms of each placement notice issued in a manner consistent with the foregoing and pursuant to which the Shares may be sold pursuant to the Agreements, (iv) issuance of the Shares pursuant to the terms established by the Board of Directors and the pricing committee thereof and the terms of the applicable placement notice, and (v) receipt by the Company of the proceeds for the Shares sold pursuant to such terms and such applicable placement notice, the Shares will be validly issued, fully paid and nonassessable.

This opinion letter has been prepared for use in connection with the filing by the Company of a Current Report on Form 8-K relating to the offer and sale of the Shares, which Form 8-K will be incorporated by reference into the Registration Statement and Prospectus, and speaks as of the date hereof.  We assume no obligation to advise of any changes in the foregoing subsequent to the delivery of this letter.

We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the above-described Form 8-K and to the reference to this firm under the caption “Legal Matters” in the Prospectus.  In giving this consent, we do not thereby admit that we are an “expert” within the meaning of the Securities Act of 1933, as amended.

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Schedule 1

KeyBanc Capital Markets Inc.

Canaccord Genuity Inc.

Deutsche Bank Securities Inc.

Goldman, Sachs & Co.

Guggenheim Securities, LLC

Jefferies LLC

J.P. Morgan Securities LLC

Merrill Lynch, Pierce, Fenner & Smith

Incorporated

Morgan Stanley & Co. LLC

MUFG Securities Americas Inc.

Raymond James & Associates, Inc.

RBC Capital Markets, LLC

Stifel, Nicolaus & Company, Incorporated

SunTrust Robinson Humphrey, Inc.

Wells Fargo Securities, LLC

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