Comparative studies on the tegument of F. fasciolaris (Pallas, 1781) and F. czaplinskii Grytner-Zięcina, 1994, using transmission electron microscopy revealed in both species examined evident differences in the morphology of the tegument surface from various parts of the cestode body (scolex, pseudoscolex, strobila). Two categories of microtriches, characteristic for both studied fimbriariids, were found: (1) typical microtriches with a well developed basal part and an osmiophilic spine at the apex, present on the scolex and on the fan-like, polar side of the pseudoscolex, and (2) non-typical spineless microtriches, present on the small, aporal part of the pseudoscolex and on the whole surface of the strobila. The presence of numerous spiny microtriches on the pseudoscolex perhaps indicates an important role for the peculiar holdfast organ, in supporting the scolex in securing the attachment of fimbriariid cestodes in the host intestine. Details of the tegument ultrastructure of Fimbriaria species are described and compared with other cestodes, and their significance is discussed.