The acute toxicity in mice and the in vitro anthelminthic effects on Haemonchus contortus worms of aqueous extracts from three (3) plants: Cassia sieberiana D.C. (Caesalpiniaceae), Guiera senegalensis J.F Gmel. (Combretaceae) and Sapium grahamii (Hochst) Pax. (Euphorbiaceae) used in traditional medicine in Burkina Faso for the treatment of gastro – intestinal parasites are reported in this study. By oral route, the extracts of plants did not present toxicity on mice up to 2000 mg / kg in 72 h. By intra peritoneal way, the 50 % lethal doses (LD50) were 273 mg / kg (leaves of Guiera senegalensis); 389 mg / kg (leaves of Sapium grahamii); 660 mg / kg (leaves of Cassia sieberiana) and 253 mg / kg (roots barks of Cassia sieberiana).The evaluation of the effects on Haemonchus contortus worms showed that at 0.1, 1, 3, 10 and 15 mg / mL, all the extracts provoked the death of the worms after 24 hours of contact. The mortality was dose dependent for the roots barks of Cassia sieberiana (ERCS) and the leaves of Sapium grahamii (FSG) and not dose-dependent for the leaves of Cassia sieberiana (FCS) and the leaves of Guiera senegalensis (FGS). The lethal concentrations (CL50) were 0.8 ± 0.4, 0.39 ± 0.4, 0.17 ± 0.1 and 1.04 ± 0.7 mg/mL for ERCS, FCS, FGS and FSG respectively. These experimental results suggested that the extracts of the studied plants possess anthelminthic properties that would justify their use in traditional medicine against the gastro intestinal parasites.