A total of 24 patients with intractable cancer pain were evaluated as candidates for spinal morphine therapy. Temporary trials were carried out with bolus injections of preservative-free morphine sulfate via percutaneously inserted epidural catheters. Fourteen patients felt that pain relief was sufficient to warrant long term morphine application, and permanent drug delivery systems were implanted. These consisted of an Ommaya reservoir and an epidural spinal catheter in 6 patients and an Infusaid pump with either an epidural or subarachnoid spinal catheter in 8 patients. Pain relief with these systems was felt to be excellent in 7 patients, good in 4 patients, and fair in 3 patients. There was statistically significant reduction in supplemental narcotic use between the pre- and postoperative periods (P < 0.001). Median survival after operation was 3.0 months (mean, 5.0 months), with a range of 1 to 23 months. Tolerance was seen in all patients regardless of the mode of drug delivery, but it occurred more quickly with bolus injections than with continuous infusion (statistically significant difference, P < 0.05). A persistent cerebrospinal fluid fistula developed in 1 patient; this required wound revision. No other serious complications or episodes of respiratory depression occurred. We conclude that intraspinal morphine sulfate is a beneficial treatment option of cancer patients in whom pain has become debilitating and unresponsive to oral or parenteral narcotic regimes.