Seventy-five patients with moderate to severe cancer pain were randomly assigned in a double-blind fashion to receive first-dose ketorolac tromethamine 10 mg orally, acetaminophen 600 mg plus codeine 60 mg orally, or placebo, followed by subsequent doses of ketorolac or acetaminophen plus codeine four times daily for 7 days. Patient characteristics were similar among the treatment groups. The first-dose observation documented that both ketorolac and acetaminophen plus codeine produced an equivalent reduction in cancer pain and were superior to placebo as measured by pain intensity differences and pain relief. Multidose comparison documented a small but statistically significant advantage in mean daily pain relief favoring acetaminophen plus codeine, although there were no differences in mean daily ratings of overall effects for either study medication. Adverse symptoms were acceptable with both ketorolac and acetaminophen plus codeine. We conclude that ketorolac has significant analgesic activity in patients with cancer pain, although its precise role in the treatment regimen of these patients remains undefined.