The purpose of this experiment was to study the anthelmintic activity of Carica papaya seeds against Hymenolepis nana in infected mice. In this experiment we use three groups (A, B, and C) of mice, group (A and B) were infected with eggs of Hymenolepis nana, PCV, Hb and W.B.C counts respectively. Group A mice were treated with Carica papaya seed extract (0.1ml ?mowe) blood and fecal samples were collected on day 0, 7 and 14 after administration of treatment to examine change in blood packed cell volume PCV Hb, W.B.C, fecal egg counts (FEC). Group C served as a no infected group (negative control). FEC of group A was lower than the control group, PCV, Hb and W.B.C increased after 7days then return to normal value after 14days. The histopathological study showed papaya repair the tissue of intestine and return the villa to normal value. The results recommended using the C.papaya as an aid to control gastrointestinal nematodes infection. Keywords: Anthelmintic activity Carica papaya, Hymenolepis nana, mice, gastrointestinal nematod
