The purpose of this study was to assess changes in liver enzyme levels among opioid-dependent patients treated with buprenorphine. Liver enzyme levels were evaluated among 120 individuals before treatment and following a minimum of 40 days of buprenorphine treatment (2, 4, or 8 mg/70 kg/day). Among patients with a history of hepatitis, AST and ALT levels significantly increased (p < .05) with buprenorphine treatment. The odds of observing an increase in AST were determined to be dependent upon buprenorphine dose (p < .05; odds ratio = 1.23 per 1 mg increase in dose). These results suggest that liver enzyme levels should be monitored carefully when patients with hepatitis are treated with buprenorphine.