Twenty-eight cancer patients were treated with intramuscular butorphanol tartrate, a new non-narcotic analgesic, for investigating its clinical benefits in controlling cancer pain. Remarkable analgesic effects were observed approximately 30 minutes after administration by the single dose of either 1 or 2 mg of butorphanol. The effects lasted actively for 3 to 4 hours. Tolerance or drug dependency was rarely recognized even in the cases receiving repeated injections of the drug. Adverse effects, such as dizziness, nausea, thirst, numbness of the hands etc, observed in 5 patients were transient and required no medication. The above results may warrant a long-term administration of the drug for controlling varieties of pain in the cancer patients.