Exhibit 5.1

	ORRICK, HERRINGTON & SUTCLIFFE LLP
	THE ORRICK BUILDING
	405 HOWARD STREET
	SAN FRANCISCO, CALIFORNIA 94105-2669 tel +1-415-773-5700 fax +1-415-773-5759

March 27, 2009

Cell Therapeutics, Inc.

501 Elliot Avenue West, Suite 4000

Seattle, Washington 98119

Re: Registration Statement on Form S-8

Ladies and Gentlemen:

At your request, we are rendering this opinion in connection with the proposed issuance of up to 26,000,000 shares of common stock, no par value (the “Shares”) of Cell Therapeutics, Inc., a Washington corporation (the “Company”), pursuant to the 2007 Equity Incentive Plan, as amended, and the 2007 Employee Stock Purchase Plan (collectively, the “Plans”) and pursuant to a Registration Statement on Form S-8 (the “Registration Statement”).

We have examined instruments, documents, and records which we deemed relevant and necessary for the basis of our opinion hereinafter expressed. In such examination, we have assumed the following: (a) the authenticity of original documents and the genuineness of all signatures; (b) the conformity to the originals of all documents submitted to us as copies; and (c) the truth, accuracy, and completeness of the information, representations, and warranties contained in the records, documents, instruments and certificates we have reviewed.

Based on such examination, we are of the opinion that the Shares to be issued by the Company pursuant to the Plans are duly authorized, and when issued and sold as described in the Plans and Registration Statement, will be legally issued, fully paid, and nonassessable.

In rendering this opinion, we have assumed that (i) the Registration Statement becomes and remains effective during the period when the Shares are offered, issued and sold, (ii) the Shares to be sold are issued in accordance with the terms of the Plans, (iii) the Company receives the full consideration for the Shares as stated in the Plans, (iv) the per share consideration for each Share includes payment of cash or other lawful consideration at least equal to the par value of the Company’s common stock, and (v) all applicable securities laws are complied with.

We hereby consent to the filing of this opinion as an exhibit to the above referenced Registration Statement on Form S-8 and to the use of our name wherever it appears in said Registration Statement. In giving such consent, we do not consider that we are “experts” within the meaning of such term as used in the Securities Act of 1933, as amended, or the rules and regulations of the Securities and Exchange Commission issued thereunder with respect to any part of the Registration Statement, including this opinion, as an exhibit or otherwise.

Cell Therapeutics, Inc.

March 27, 2009

Page 2

Very truly yours,

/s/ Orrick, Herrington & Sutcliffe

Orrick, Herrington & Sutcliffe LLP