In the paper the author presents a critical analysis of some characters, widely used in taxonomy of Prosobranchia, as: shell architecture, external morphology of cephalopodium, heart and mantle cavity organisation, ctenidium, osphradium, kidney, radula, digestive system, cen­tral nervous system, and male as well as female reproductive organs. The analysis is mainly based on the author’s studies on the Polish freshwater prosobranchs. The author points out limitations of usefulness of practically all characters for recognition of the real phyletic relationships between the higher prosobranch taxa. Then the author proposes some new charac­ters based on SEM shell studies: protoconoch and teleconch outer surface sculpture, teleconch inner surface sculpture, and structures visible in shell cross-sections. The structures as well as radulae are presented in 84 SEM photographs. The outer and inner surfaces of both the proto- and teleconch turned out to be rather poorly differentiated and more variable within than between families, while the organisation pattern of shell cross-sections seemed characteristic for a given family and then a good character, not less useful in family grouping than good “classic” ones.