Nineteen patients with advanced head and neck cancer were given mitozolomide (MTZ), i.v. infusion, every 6 weeks. The starting dose was 100 mg m-2. When it was well tolerated, dose escalation was performed up to 110-115 mg m-2. The limiting toxicity was thrombocytopenia, often mild, but occasionally severe, with hemorrhage and the need for platelet transfusions in two patients. The platelet nadir was 85 x 10(9) l-1 (11-225). No response was observed in 14 evaluable patients. MTZ, according to this schedule and dosage does not show significant activity in human squamous cell head and neck cancer.