The paper deals with content of certain lipid groups (triacylglycerols (TAG), diacylglycerols (DAG), non-etherified fatty acids (NEFA) and phospholipids (PhL)) in body of the freshwater mollusks <i>Lymnaea stagnalis</i> (Linnaeus, 1758), and <i>Unio pictorum</i> (Linnaeus, 1758), which differ in anatomical and morphological structure, ecological features, nutrition spectra and motor activity.
The lipid composition of the mollusks is species specific and significantly varies in the considered organs. The lipid content in <i>U. pictorum</i> organs differed in males and females.