The diseases caused by protozoans are of great concern to the public health in Brazil. Our research group is currently investigating the antiprotozoal potential of some Brazilian plants. Within this context, we evaluated the antiprotozoal activity of stem extracts of Aspidosperma tomentosum Mart. (Apocynaceae). The plant is used by the population to treat malaria, leishmaniasis, fever and rheumatism (Albernaz et al., 2010). Indole alkaloids have been described in this species. The dried powder of A. tomentosum stems was extracted by percolation using MeOH:water (8:2) and lyophilized. The extract was solubilized in HCl (0. 1M and the solution was extracted by partition with CH2Cl2 (F1). The aqueous phase was alkalized (pH 10) and extracted with CH2Cl2 (F2), EtOAc (F3) and BuOH (F4). The obtained extracts (F1, F2, F3 and F4) were evaluated for antiprotozoal activity. The assays were carried out according to previously described procedures (Mesia et al., 2008). The samples were evaluated by TLC after spraying Dragendorff reagent. According to the results, F1 was active against Plasmodium falciparum (IC50 8.91 µg/mL), Trypanossoma cruzi (IC50 6.30 µg/mL) and Leishmania infantum (IC50 8.11 µg/mL). However, the extract was cytotoxic on peritoneal murine macrophages (PMM, IC50 8.0 µg/mL) and human fetal lung fibroblasts (MRC-5, IC50 10.96 µg/mL). F2 was more active than F1 against P. falciparum KI strain (IC50 2.27 µg /mL), T. cruzi (IC50 7.18 µg/mL) and L. infantum (IC50 9.51 µg/mL). F2 was less cytotoxic than F1 in PMM (IC50 32 µg/mL) and MRC-5 (IC50 27.52 µg/mL). In both extracts alkaloids were detected by TLC. The ethnopharmacological use of Aspidosperma tomentosum and our results obtained are consistent. Ongoing experiments are being performed to isolate the active compounds even though the extracts were cytotoxic in the available models.