Abstract As a result of preclinical data demonstrating the antitumour and antimetastatic efficiency of indomethacin in murine models, and the clinical observation of occasional tumour regression in patients with advanced melanoma treated with indomethacin together with ranitidine, a Phase II study was performed of prolonged administration of these two oral agents in combination. Seventeen patients were entered into the study and commenced on indomethacin 50 mg three times daily; the dose was escalated to a maximum of 75 mg three times daily in patients who tolerated the starting dose. Ranitidine was administered concurrently at a dose of 150 mg twice daily. One patient with uveal melanoma metastatic to the liver achieved a partial response, with slow shrinkage of a biopsy-proved liver metastasis (objective response rate 6%; 95% CI 0–29). Another patient demonstrated a minor response in pelvic lymph nodes. The combination of indomethacin and ranitidine has negligible activity in advanced malignant melanoma; a response may require months to be achieved.