Epidural injection of narcotics for postoperative pain relief has been well reported. Caudal nalbuphine was assessed as a postoperative analgesic in a randomized double blind study of 80 patients after perianal surgery. Caudal block was carried out with 1.5% lidocaine 25 ml (Group 1) in 20 patients, and mixed with nalbuphine 3 mg (Group 2) in 20 patients, nalbuphine 5 mg (Group 3) in 20 patients, and nalbuphine 10 mg (Group 4) in 20 patients. Pain relief was evaluated by the subsquent need for systemic analgesics (Pethidine). In group 4, the use of systemic analgesics was significantly reduced for the first 24 hours postoperatively. Urinary retention was not correlated with nalbuphin dose.