Theodoxus schultzii (Grimm, 1877), one of the rarest gastropod species of the Caspian Sea, is redescribed from recently sampled material. Morphological features are described, with photographs of the shell, operculum and radula. The shell of this species is characterised by its mostly citreous colour and elongation of the apertural edges. In its typical form, it is very similar to other species of the genus. The features of the radula and operculum are very similar to those of T. pallasi Lindholm, 1924 from the Caspian Sea and T. astrachanicus Starobogatov, 1994 from the Volga delta.