Abstract: In this study we investigated the acute and subchronic toxicity of hydroalcoholic (50-50: v/v) extract of Lannea kerstingii Engl. and K. Krause (Anacardiaceae) stem bark in Wistar rats. In the acute test, the dose of 5.000 mg kg-1 was used for the test limit. Animals were then observed individually 1 h post dosing and at least once daily for 14 days. The subchronic toxicity was evaluated through biochemical, haematological, body and relative organ weight of rats using daily oral doses of 500 and 1000 mg kg-1 b.wt., during 28 days. The limit dose of 5.000 mg kg-1 did not cause mortality or any sign of acute toxicity in any of the rats tested in the observatory period. In the subchronic test, L. kerstingii at 1000 mg kg-1 decreased significantly (p<0.05) the increment of body weight of rats from the 2nd to the 4th week. The decrease of the increment was 11, 11 and 10% on the 2nd, 3rd and 4th week, respectively. The relative weight of the spleen in the group treated with 1000 mg kg-1 b.wt. (0.19±0.01) showed a significant increase (p<0.05) as compared to control group (0.15±0.01). Biochemical and haematological parameters measured were similar between the control and treated groups.