This study investigates the action of Canova medication (CM) on experimental infection by Leishmania (Leishmania) amazonensis, utilizing in vitro and in vivo assays. For the in vitro tests, Balb/c mouse peritoneal macrophages (5x10(5) cells in 500 microl of culture medium, supplemented with 10% fetal calf serum, penicillin (100 U/ml) and streptomycin (0.1 mg/ml) (were distributed in 24-well plates and CM was added at concentrations of 20 or 40%. Twenty-four hours later, the macrophages were infected with Leishmania amastigotes in culture medium. The effect of CM on macrophages leishmanicidal activity in 24 and 48 h cultures was evaluated by determining infection index and measuring nitric oxide (NO) production. The in vivo tests were performed in mice infected with 10(7)L. (L.) amazonensis promastigotes injected in to the right hind footpad (25 microl in phosphate buffered saline). The progression of the lesions was examined over a 9-week period by measuring footpad swelling, and the parasite load in regional lymph nodes and spleen. The in vitro results showed that at 40% CM reduced the infection index, and induced NO production in the elicited macrophages, which suggests that the inhibitory effect on infection index may be mediated by NO. In the in vivo infection, when administered, orally or subcutaneously in mice, CM reduced infection by L. (L.) amazonensis in the paws, resulting in smaller lesions. CM treatment also decreased parasite load in the regional popliteal lymph nodes and in the spleen. These results suggest that CM modulates experimental infection by L. (L.) amazonensis, controlling infection progression and limiting dissemination.