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EXHIBIT - 23.1
CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
As independent public accountants, we hereby consent to the incorporation by
reference in this registration statement on Form S-3 of our reports dated March
6, 2000 (except with respect to the matters discussed in Note 15 to the
consolidated financial statements, which are indicated to have occurred
subsequent to March 6, 2000, as to which the date is March 20, 2000) included in
CAIS Internet, Inc.'s Form 10-K for the year ended December 31, 1999 and to all
references to our Firm included in this registration statement.
ARTHUR ANDERSEN LLP
Vienna, Virginia
May 31, 2000
