Hepatotoxic effects of chromium have been studied on the liver function enzymes of male New Zealand white rabbits, Oryctolagus cuniculus, with and without pretreatment with phenobarbitone (PB) and promethazine (PM). The total body weight was decreased under all experimental conditions. After PB administration (5 mg/kg body wt/day for 5 days), the serum glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), lactate dehydrogenase (LDH), and isocitrate dehydrogenase (ICDH) activities decreased 21%, 65%, 25%, and 37%, respectively, whereas the alkaline phosphatase (AP) activity increased 70%. After PM treatment (5 mg/kg body wt/day for 5 days) the serum GPT was inhibited 73%, whereas LDH activity was increased 37%. The hepatic GPT and AP activities decreased after PB (52% and 31%, respectively), and PM (48% and 44%, respectively) treatments, whereas the activities of LDH and ICDH increased (after PB: 817% and 109%, respectively, and after PM: 136% and 44%, respectively). Potassium dichromate, administered at a dose of 8 mg/kg body wt/day for 5 days, decreased serum GOT (44%), GPT (61%), LDH (63%), and AP (44%) activities. The hepatic GOT, GPT and AP activities were likewise decreased (86%, 51%, and 46%, respectively), whereas hepatic LDH and ICDH activities increased 667% and 193%, respectively. When administered to PB-pretreated animals, the serum GOT and AP activities were decreased (50% and 68%), whereas ICDH was increased (29%). The hepatic GOT, LDH, and ICDH activities increased 79%, 221%, and 130%, respectively. In the PM-pretreated animals, the chromium treatment inhibited the activities of serum GOT (48%), GPT (44%), and LDH (43%). The hepatic GPT, LDH, and ICDH activities increased 90%, 133%, and 52%, respectively.