Buprenorphine is a mixed agonist-antagonist with high affinity at both mu and kappa opiate receptors. Its pharmacological profile is determined primarily by partial agonism at mu-receptors and unusually slow kinetics at these receptors. Its intrinsic activity is such that in nearly all clinical situations it is as effective an analgesic as morphine with considerably longer duration and much more favourable acute safety. In long-term dosing studies in rodents and primates buprenorphine did not produce the manifestations of physical dependence when treatment was stopped. In self-administration studies in the same species only limited levels of reinforcing efficacy were demonstrated when compared with the opiates. In human former opiate addicts the limited potential of buprenorphine to produce psychological dependence was confirmed as was the favourable physical dependence profile. Some misuse of buprenorphine has been reported in 3 of the 29 countries in which buprenorphine is marketed despite its wide clinical acceptance, particularly as the sublingual formulation.