An analgesic composition, in parenteral unit dosage form or in a unit dosage form suitable for delivery via the dermis or mucosa, comprises buprenorphine and an amount of naltrexone such that the ratio by weight of buprenorphine to naltrexone delivered to or reaching the plasma of a patient is in the range 100:1 to 5000:1. The analgesic action of the buprenorphine is potentiated by the low dose of naltrexone. Also provided are a method of treatment of pain and the use of buprenorphine and naltrexone for the manufacture of a medicament.