Abstract: Myrrh is an oleoresin gum extracted from a tree known as Commiphora molmol. In the present study the effects of myrrh on mice infected with 100 cercariae of Schistosoma mansoni (S. mansoni) were studied. We found that serum antischistosomal antibodies of mice infected with Schistosoma mansoni was decreased significantly (p<0.0001) after three weeks of the treatment with myrrh (10 mg/kg body weight) as well as praziquantel (PZQ) (250 mg kg-1 body weight) compared with the infected non-treated group (control group). The mean serum level of IL-2 was decreased significantly after treatment with PZQ and myrrh (p<0.05; 0.01, respectively). On the other hand, the level of gamma interferon (IFN-γ) did not affected by the treatment with PZQ but decreased non significantly after treatment with myrrh. In conclusion myrrh can improve the cellular immunity of schistosomiasis infected mice.