Ketorolac tromethamine is a newly available non-steroidal anti-inflammatory drug which is suitable for parenteral administration. We have given it by continuous subcutaneous infusion to 36 patients with pain due to advanced cancer. Improvement in pain control occurred in 29 (80%). A reduction in the dose of concomitant opioid analgesia was possible in 22 (76%) and a reduction in opioid-related adverse effects occurred in 16 (73%) of these. Ketorolac was most effective in patients who had bone or visceral pain. It was mixed safely with diamorphine in a syringe driver at concentrations up to 4 g diamorphine/10 ml and 120 mg ketorolac/10 ml. Infusion was well tolerated for periods of up to 115 days (mean 21 days; median 15 days; range 3-115 days). Four patients experienced gastrointestinal bleeding and one colonic perforation to which treatment with ketorolac may have been a contributory factor. No other clinically significant adverse effects were observed.