Opioid rotation is increasingly becoming an option to improve pain management especially in long-term treatment. Because of insufficient analgesia and intolerable side effects, a total of 42 patients (23 male, 19 female; mean age 64.1 years) suffering from severe musculoskeletal (64%), cancer (21%) or neuropathic (19%) pain were converted from high-dose morphine (120 to >240 mg/day) to transdermal buprenorphine. The dose of buprenorphine necessary for conversion (at least 52.5 microg/h) was titrated individually by the treating physician. No conversion recommendations were given and the treating physician used his or her own judgment for dose adjustment. Pain relief, overall satisfaction and quality of sleep (very good, good, satisfactory, poor, or very poor), and the incidence and severity of adverse drug reactions over a period of at least 10 weeks and up to 1 year was assessed. Following rotation, patients experiencing good/very good pain relief increased from 5% to 76% (P < 0.001). Only 5% reported insufficient relief. Relief was achieved with buprenorphine alone in 77.4%, while 17% needed an additional opioid for breakthrough pain. Sleep quality (good/very good) increased from 14% to 74% (P < 0.005). Adverse effects were reported in 11.9%, mostly because of local irritation, did not result in termination of therapy. Neither tolerance nor refractory effect following rotation from morphine to buprenorphine was noted. Conversion tables with a fixed conversion ratio are of limited value in patients treated with high-dose morphine.