The <i>in vitro</i> antiprotozoal and cytotoxic activity of the aqueous extract, the 80% methanol extract, and its different soluble fractions and subfractions from <i>Brucea sumatrana</i> seeds were assessed against two Trypanosoma (<i>T. cruzi</i> and <i>T. brucei brucei</i>), <i>Leishmania infantum</i> and chloroquine and pyrimethanine-resistant K1strain of <i>P. falciparum</i> and against MRC-5 cell-lines respectively. Results indicated that the 80% methanol extract showed a cytotoxic effect against MRC-5 cell lines with CC₅₀ value of 0.54 µg/ml. It however exhibited pronounced and non selective activity against <i>T. cruzi</i> (IC₅₀ = 1.52 µg/ml, SI = 0.03) and <i><i>L. infantum</i></i> (IC₅₀ = 2.41 µg/ml, SI = 0.22). It however displayed pronounced and selective effect against T. brucei brucei (IC₅₀ < 0.25, SI > 2.16) and chloroquine and pyrimethamine-resistant K1 strain of <i>P. falciparum</i> (IC₅₀ < 0.25 µg/ml, SI > 2.16). All soluble fractions and subfractions from the partition of the 80% methanol extract were found to exhibit an antiprotozoal activity with IC₅₀ values ranging from <0.25 to 30 µg/ml. The most active was the alkaline aqueous soluble fraction exhibiting pronounced antiprotozoal activity against <i>T .cruzi</i>, <i>T. b. brucei</i>, <i>L. infantum</i> and chloroquine and pyrimethamine-resistant K1 strain of <i>P. falciparum</i> with IC₅₀ values of 0.33, <0.25, 0.25, <0.25 µg/ml respectively resulting in high selective index values of 61.36, > 81, 81 and >81 respectively. The chloroform soluble fraction rich in alkaloid was cytotoxic against MRC-5 cell lines (CC₅₀ = 27.09 µg/ml) and showed good activity against T. b. brucei (IC₅₀ = 8.36 and SI = 3.24) and moderate activity against <i>T. cruzi</i>, <i>L. infantum</i> and chloroquine-pyrimethane-resistant K1 strain of <i>P. falciparum</i> (20 < IC₅₀ < 30 µg/ml). Although the aqueous extract (decoction) and the total alkaloids extract showed a cytotoxic effect against MRC-5 cell lines (CC₅₀ = 1.55 and 0.43 µg/ml respectively), they however displayed pronounced antiprotozoal activity against <i>T. cruzi</i>, T. b. brucei and chloroquine and pyrimethamine-resistant K1 strain of <i>P. falciparum</i> with IC₅₀ values ranging from < 0.25 to 0.6 µg/ml with only a selective action against chloroquine and pyrimethamine-resistant K1 strain of <i>P. falciparum</i> (SI = >6.2 and >1.72 respectively). These extracts however showed good and low activity respectively against <i>L. infantum</i> (IC...