Retinoids, the analogs of vitamin A, are active in vitro and in vivo against squamous cell carcinoma in animals and against certain epithelial precancers and cancers in humans. These data led us to design a prospective, multi-institutional, randomized phase II trial of isotretinoin in advanced head and neck squamous cell carcinoma. We randomly assigned 40 patients to receive isotretinoin or methotrexate, the best-studied and most active single agent for this disease. Overall, the study patients had extremely poor prognoses, i.e., low performance statuses and recurring disease after surgery and/or irradiation. Three objective responses (16%), including one complete response, occurred in the 19 evaluable isotretinoin-treated patients. Only one minor response (5%) occurred in the methotrexate-treated group. Toxicity occurred with both drugs, but was manageable and never life threatening in the retinoid group. These results and the established activity of retinoids in oral leukoplakia (a precursor of head and neck cancer) indicate the need for further study of this class of drugs in head and neck cancer.