Activities of F. exasperata (Vahl) leaf extract on the liver function of albino rats were studied. Thirty two mature albino rats weighing between 130-150g were divided into four groups of eight rats. Group 1 (control) received 0mg/kg BW, and Group 2 received 50mg/kg BW, Group 3 received 100mg/kg BW, and Group 4 received 150mg/kg BW for 8 weeks. The rats in each group were sacrificed and blood samples collected by cardiac puncture into heparinized sample bottles. The results showed that the leaf extract of F. exasperata caused significant effect (P< 0.05) on Aspartate aminotransferase (AST), alkaline phosphatase (ALP), alanine transaminase (ALT), total bilirubin and conjugated bilirubin levels. The histological architecture of the liver and kidney cortex revealed several damages, especially in the kidney cortex. This is an explicit indication that the use of F. exasperata leaf extract in herbal medicine without proper scientific evaluation might be dangerous to health.