The use of petroleum samples as medicaments either due to poverty or ignorance is becoming a source of worry. Unfortunately, the elderly and children are most vulnerable. Crude petroleum is usually given to some children when they convulse as anticonvulsant. Incidentally, the liver is the site where most drugs and other ingested substances are metabolized and detoxified. It was based on this, that some liver function enzymes such as the transaminases and alkaline phosphatase activities were employed to assess the state of the liver in albino rats after exposure to crude petroleum (Bonny light). The rats were placed in four groups and were intraperitoneally administered 6.0, 12.0 and 30.0gkg-1 of crude petroleum (Bonny light) respectively, for 2 phase periods of 1and 2 months. .At the end of each period, rats were withdrawn from each group for analysis. The control rats were similarly treated with normal saline. Blood samples were taken for serum enzymes aspartate transaminase (AST), alanine transaminase (ALT), and alkaline phosphatase (ALP). The results revealed significant increases in the activities of AST and ALP in rats exposed to crude petroleum in a dose-dependent manner, compared with control (P<0.05). Similarly, significant increase in bilirubin level was observed in the groups treated with crude petroleum (Bonny light). The second month values were proportionately higher than the first.