The therapy of metastatic melanoma is limited by poor responses to known chemotherapeutic agents. The report of Mulder et al. (Proc ASCO 1992; 11: 347) raised the possibility of the known interaction between 5-fluorouracil and interferon-alpha2a improving response rates in melanoma. This study was designed to examine the effects of 5-fluorouracil plus interferon-alpha2a alone without the confounding effects of dacarbazine. Doses were chosen based on the earlier study rather than the higher doses used in colon cancer. Therapy for metastatic melanoma with 5-fluorouracil and interferon-alpha2a is manageable in terms of toxicity. The major toxicities were lethargy, nausea/anorexia and flu-like symptoms. These were thought to be primarily attributable to interferon-alpha2a. Only one case of severe diarrhoea occurred. The response rate of 14% is similar to the reported results of interferon-alpha2a treatment alone. On these data, there is no evidence of synergy using this dose and schedule.