Preclinical and clinical data have suggested antitumor efficacy in squamous cell carcinoma (SCC) of interferon (IFN)-alpha and 13-cis-retinoic acid (13-c-RA) as single agent with greater activity in combination. Cisplatin was added to potentiate activity. Twenty-three patients with pretreated advanced or metastatic head and neck squamous cell carcinoma were given a combination of IFN-alpha (6 x 10(6) U/day, 84 days s.c.), 13-c-RA (1 mg/kg/day, 84 days) and cisplatin (40 mg/kg/day, day 1, 28 and 56). Seventeen patients had discontinuation of treatment and three patients received overall treatment without dose reduction. Hematological toxicity was more frequent; only three patients experiencing grade 3 or higher extra-hematological toxicity. Four out of 14 evaluable patients were in response, with one in complete pathological response. Median duration of response was 6 months with a 9 month median survival. Association of IFN-alpha, 13-c-RA and cisplatin induces modest but definite antitumor activity with moderate and manageable toxicity. Further studies of different combination modality therapy with chemotherapy and differentiating agents need to be performed in less pretreated patients.