Sixteen species of Haliplidae belonging to three genera are recorded from Colorado: *Brychius hornii Crotch, Peltodytes callosus (LeConte), P. edentulus (LeConte), *P. litoralis Matheson, *Haliplus apicalis C.G. Thomson, *H. canadensis Wallis, H. cribrarius LeConte, H. deceptus Matheson, *H. distinctus Wallis, H. fulvus Fabricius, H. immaculicollis Harris, H. leechi Wallis, H. longulus LeConte, *H. stagninus Leech, *H. tortilipenis Brigham and Sanderson, and H. triopsis Say. Seven of these species (*) represent new state records, and H. distinctus is reported from the United States for the first time. Haliplids found in Colorado generally fit one of the following distributional patterns for North America: Western, representing 31% of the species, Northern (31%), Eastern-Midwestern (25%), and Holarctic (13%). Diagnostic characters, habitat information, and both Colorado and North American distributions are discussed for each species. Statewide distributional maps and an identification key are provided for adults recorded from the state. The aedeagus is shown to be the most reliable character for identification of Haliplus males, and a photomicrograph of the aedeagus is provided for each Colorado species. Three species previously reported from Colorado, H. dorsomaculatus, H. salmo and H. robertsi, are unconfirmed, and three additional species, P. dispersus, P. tortulosus, and H. borealis whose known distributions suggest they may occur in Colorado, are discussed.