Eight species of Monogenea (Dactylogyridae) are reported from the gills of freshwater fishes from Colombia as follows: Anacanthonis colombiamis sp. n. from Salminus affinis Steindachner and Tilapia mossambica (Peters); A. cuticulovaginus sp. n. from S. affinis; Cichlidogyrus sclerosus Paperna and Thurston, 1969, and C. tilapiae Paperna, 1960, both from T. mossambica; Urocleidoides costaricensis (Price and Bussing, 1967) Kritsky and Leiby, 1972, U. hcteroancistrium (Price and Bussing, 1968) Kritsky and Leiby, 1972, and U. strombicirrus (Price and Bussing, 1967) comb. n. (all) from Astyanax fasciatus (Cuvier); and U. anops sp. n. from Characidium caucanum Eigenmann. C. sclerosus and C. tilapiae are recorded for the first time from the western hemisphere.