Abstract: Scanning electron microscopy (SEM) succeeds in revealing novel microtopographical features of the
host-parasite relationship, as well as proving invaluable in helminthes taxonomy. Hymenolepis nana and
H. diminuta are commonly maintained in laboratory rodents and used in many experimental model systems of
tapeworms infections. In the present work, the length of worm of Hymenolepis nana and H. diminuta were
approximately up to 1-3 cm × 1mm and 6 cm × 3.5 mm, respectively. The SEM revealed that the scolex of H. nana
and diminuta appears roughly rectangular and is provided with an armed suker and rostellum. The rostellum
is provided with hymenolepid hook in H. nana and an unhooked rostellum in H. diminuta. These suckers
occupy the corners of the rectangular scolex. Fine structural of the tegumental surface of both H. nana and
H. diminuta is densely covered with microtriches which are of the same shape and were never seen to
be branched. SEM of intestinal mucosa of infected rat with H. nana revealed alteration in villous architecture.
The purpose of this study is to use SEM technique as advanced approach for differentiating between H. nana
and H. diminuta.