The plant was investigated for possible toxicity (both acute and subacute toxicity) in wistar rats. Twenty five female rats were divided into five groups of five rats each. The first group was orally dosed with 2000 mg/kg body weight of the extract for acute toxicity testing. The remaining four groups were used for subacute testing and were dosed as follows; group A received orally administered distilled water, group B received 50mg/kg, and groups C and D received 100 and 200 mg/kg respectively of the extract orally. All animals survived the acute and subacute toxicity testing but histopathological changes were seen in the liver, kidney, spleen, and lungs of all the treatment groups. Haematological and biochemical parameters were also altered in all treated groups. This experiment suggests that the leaves of Guiera senegalensis do have toxic effects despite its wide use in African traditional medicine.