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                                                                    EXHIBIT 23.3

                        CONSENT OF INDEPENDENT AUDITORS

We consent to the reference to our firm under the caption "Experts" in
Post-Effective Amendment No. 1 to the Registration Statement (Form S-3, No.
333-47858) and related Prospectus of USinternetworking, Inc. for the
registration of up to $150,000,000 of common stock, and to the incorporation by
reference therein of our report dated March 23, 1999, with respect to the
consolidated financial statements of I.I.T. Holding, Inc. and subsidiaries
included in the Annual Report (Form 10-K) of USinternetworking, Inc. for the
year ended December 31, 2000, filed with the Securities and Exchange Commission.

                                                           /s/ Ernst & Young LLP



Baltimore, Maryland
June 15, 2001