The effects of levamisole on the histopathological changes, host's resistance and "in vivo" chemotaxis in Schistosoma mansoni experimental infection of C57B1/10 inbred mice were studied. Prophylatic treatment resulted in an increase in the number of adult worms obtained by perfusion and also increased the mortality rate (p < 0.05). The histopathological changes (liver and intestines) were similar in all the groups. A significant reduction of "in vivo" chemotaxis occurred in infected control mice as well as in those submitted to prophylatic treatment with levamisole. Chemotatic activity reached the same levels of normal control mice (non-infected and non-treated with levamisole), when the curative scheme was used. Levamisole seems to increase the susceptibility of inbred C57B1/10 mice to the infection with S. mansoni when administered prior to the infection and increase the chemotatic activity to normal levels when given after infection.