Type specimens of Baetis obtusiceps, B. obscuriventris, B. diversicolor and B. mongolicus have been reexamined; lectotypes of B. obtusiceps, B. obscuriventris and B. mongolicus are designated. The following new synonymy is suggested: Baetis vernus Curtis, 1834 = B. obtusiceps Tshernova, 1952, syn. n.; Baetis fuscatus (Linnaeus, 1761) = B. diversicolor Tshernova, 1952, syn. n.; Labiobaetis tricolor (Tshernova, 1928) = Baetis obscuriventris Tshernova, 1952; = B. mongolicus Tshernova, 1952, syn. n.