The leaves of Houttuynia cordata Thunb.(Saururaceae) are considered to have anthelmintic proper-ties in the traditional medicine of Naga tribes in Northeast India and, therefore, are used by the natives to treat the intestinal worm infections. In the present study, the anti-cestodal activity of H. cordata leaf extract was investigated against Hymenolepis diminuta, a zoonotic cestode, in experimentally infected albino rats. For the assessment of anticestodal efﬁcacy, the eggs per gram (EPG) of faeces counts and worm loads of animals were monitored fol-lowing treatment with 200, 400 and 800 mg/kg p.o. doses of leaf extract to different groups of rats harbouring larval, immature and mature H. diminuta infections. The efﬁcacy of the extract was found to be dose-dependent (P < 0.05). Further, the extract showed its maximum efﬁcacy against the mature Hymenolepis worms. In this case, the 800 mg/kg dose of extract signiﬁcantly reduced (P < 0.001) the EPG counts of animals by 57.09% and worm load by 75.00%, at post-treatment. In comparison, the reference drug praziquantel at 5 mg/kg showed a reduction in the EPG counts and worm load of experimental animals by 80.37 and 87.50%, respectively. These ﬁndings indicate that leaves of H. cordata possess signiﬁcant anticestodal property and provide a rationale for their use in traditional medicine as an anthelmintic.