The effect of administration of aqueous extract of Hippobromus pauciflorus (L.f.) Radlk (Sapindaceae) leaves at 50, 100 and 200 mg/kg body weight for 14 days on some biochemical parameters in male Wistar rats was investigated. The extract at all the doses tested did not significantly (P>0.05) alter the levels of white blood cells, red blood cells, mean corpuscular volume, platelets, neutrophils, monocytes, lymphocytes and large unstained cells. While the levels of haemoglobin, packed cell volume and basophils increased significantly (P<0.05) at specific doses, the mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and eosinophils decreased significantly (P<0.05). Again, the extract did not significantly (P<0.05) alter the computed liver- and kidney-body weight ratios, sodium, chloride and total protein, though, the levels of potassium, inorganic phosphorus, globulin, urea, total and conjugated bilirubin increased significantly (P<0.05) at certain doses. In contrast, the levels of albumin and creatinine also decreased significantly (P<0.05) at specific doses. While the activities of alkaline phosphatase, gamma glutamyl transferase and alanine aminotransferase remained significantly (P<0.05) unaltered in the serum, aspartate aminotransferase activity increased only at 200 mg/kg body weight. The atherogenic index as well as the concentrations of cholesterol, high- and low-density lipoprotein cholesterol in the serum of the animals were not significantly (P>0.05) altered. However, the extract significantly (P<0.05) increased the concentration of triacylglycerol. The results suggest that the extract has mild and dose specific haemato-, hepato- and nephrotoxic effects and may not be completely safe as oral remedy at the doses investigated.