Background There is evidence regarding the abuse potential of buprenorphine in prison settings. There is also emerging evidence from community settings that buprenorphine/naloxone is less amenable to abuse than the single preparation buprenorphine hydrochloride as evidenced by cost-differentials of diverted medication. This study sought to explore cost-differentials within a prison setting of diverted buprenorphine/naloxone medication relative to either single preparation buprenorphine hydrochloride or methadone. Methods Cross-sectional survey in one remand prison. Results A total of 85 prisoners participated in the survey. Prisoners estimated buprenorphine to have a significantly (p < 0.001) higher cost than buprenorphine/naloxone both ins...