Abstract: Carpolobia lutea (CL) (Polygalaceae) leaf is proven pharmacologically as possessing anti-diarrheal properties. Sub-acute toxicological investigations were executed with the Crude Ethyl Acetate Extract (CEAE) and Ethyl Acetate Fraction (EAF) which earlier reports reveal potent pharmacological activities. The pathological changes were investigated in rodents over a period of 28 days adopting Good Laboratory Practice (GLP) conditions. Thirty adult male and female Wistar rats were randomized to four treatment groups of 6 rats/equal sex/group and were administered orally with three doses of CEAE, 192.5, 385.0, 770 and one dose of EAF 770.0 mg kg-1; while 10 mL kg-1 of 20% Tween 80 was used for the control test. Weekly relative body weights were evaluated. Blood samples were collected weekly for hematological examination. At autopsy, the major organs were carefully excised and weighed. Sections were collected for histological analysis. No visible sign of behavioral toxicity were observed during study. The acute toxicity study (LD50) shows that median lethal dose is 3850.0, 3240.4 and 1414.2 mg kg-1 for the ethanol fraction, crude ethyl acetate extract and ethyl acetate fraction, respectively. Body weight but not organ weight increased significantly (p<0.05-0.001). The levels of Aspartate Amino Transferase (AST), Alanine amino transferase (ALT), Alkaline phosphatase (ALP), total and conjugated bilirubin, total protein, albumin and BUN increased significantly (p<0.05-0.001) and dose dependently. The EAF has high acute toxicity and significant biochemical but not haematopoietic sub-acute toxicological effect on oral administration in rats. Its pharmacological and therapeutic effectiveness is not without toxicity implication.