Fossil water scavenger beetles (Coleoptera: Hydrophilidae) of the latest Oligocene Rott Formation are revised, based on the examination of the type specimens, as well as numerous additional material from Statz (Los Angeles) and Kastenholz (Bonn) collections. Seven hydrophilid species are recognized, five of which are reliably attributed to the following genera: Berosus morticinus (von Heyden and von Heyden, 1866), Paracymus excitatus (von Heyden and von Heyden, 1866), Paracymus sp., Hydrobiomorpha fraterna (von Heyden, 1859), and Hydrophilus rottensis (Statz, 1939). Coccinella? protogaeae Germar 1837 is attributed to the subtribe Hydrophilina, and Cymbiodyta? austera Statz 1939 to the subfamily Hydrophilinae. Hydrous ebeninus Statz 1939 and Paracymus excitatus (form 3) are excluded from the Hydrophiloidea. Berosus capitatus Statz 1939 is synonymized with Berosus morticinus, and Hydrous neptunus von Heyden and von Heyden 1866 with Hydrobiomorpha fraterna. Lectotypes of Philydrus morticinus von Heyden and von Heyden 1866 and Hydrous ebeninus Statz 1939 are designated. The significance of the hydrophilid fossils for paleoecological reconstructions of the former Rott Lake is briefly discussed.