To study buprenorphine (Temgesic) and its metabolite, samples were previously screened by radioimmunoassay for buprenorphine. In addition, a study was undertaken to examine possible interferences from a number of other regulated drugs commonly encountered in forensic toxicology. Buprenorphine and its metabolite were synthesized in the laboratory using a high-performance liquid chromatograph equipped with an injector. A straight calibration graph was obtained for the HPLC method by plotting the area under the curve ratios of both buprenorphine and its metabolite to the internal standard versus the buprenorphine and metabolite concentrations. The graphs were linear up to a concentration of 100 ng/mL. The measured concentration of buprenorphine and its metabolite in spiked urine samples ranged from 86 to 98 percent. Detection limits were 0.2 ng/mL for buprenorphine and 0.15 ng/mL for the metabolite. The authors conclude that the HPLC method constitutes a valuable approach to confirming buprenorphine in prescreened urine samples by radioimmunoassay. 22 references, 1 table, and 2 figures (Author abstract modified)