Objective: Aqueous leaf extract of Senna alata at 250, 500 and 1000 mg/kg body weight was evaluated for toxicity in pregnant Wistar rats. Methods: Pregnant rats were grouped into four (A, B, C and D) of five animals each such that rats in groups A, B, C and D received 0.5 ml of distilled water, 250, 500 and 1000 mg/kg body weight of the extract respectively, from days 10-18 post-coitus. Results: The extract reduced (P__ampersandsignlt;0.05) the activities of alkaline phosphatase, aspartate transaminase, alanine transaminase and gamma glutamyl transferase in the liver and kidney of the animals with increases in heart and serum enzymes. The levels of haematological parameters, serum albumin, globulin, creatinine, sodium, calcium, chloride ions, blood urea nitrogen (BUN): creatinine ratio, total cholesterol, triacylglycerol, low- and high-density lipoprotein cholesterol were decreased by the extract while those of urea, uric acid, serum total bilirubin, phosphate, potassium, calcium and atherogenic index increased significantly. The myocardial fibres were normal in the heart while there was varying degree of necrosis of the tubular epithelial cells in the kidney and hepatic degeneration in the liver. Conclusion: The extract caused both functional and structural toxicities and therefore not safe for consumption during pregnancy.