Nineteen patients with measurable and incurable head and neck carcinoma (17 squamous cell and two adenoid cystic) received intravenous bolus doses of 14 mg/m2 mitoxantrone in the first course. The doses were escalated or de-escalated by 2 mg/m2 in subsequent courses, based on leukocyte nadir, to achieve mild (3,000-3,999/mm3) or moderate (2,000-2,999/mm3) toxicity and response. The courses were repeated every 3 weeks. All 60 courses were evaluated for toxicity. Leukopenia was mild, moderate, severe (1,000-1,999/mm3), and life-threatening (less than 1,000/mm3) in 17%, 23%, 42%, and 2% of courses, respectively. Mild thrombocytopenia (100,000-129,999/mm3) occurred in two courses. The median interval to nadir leukopenia was 14 days (range 7-36) with a median of 13 days (range 3-50) to recover to normal. After the first course, leukopenia was mild in 16%, moderate in 32%, severe in 26%, and life-threatening in 5%. One patient died of pulmonary embolism 8 days after the first course and had concomitant leukocyte count of 700/mm3. Eighteen patients had at least one course resulting in leukopenia. Three of six patients receiving greater than or equal to 4 courses (cumulative dose 56-102 mg/m2) had an asymptomatic decrement of 14%, 17%, and 29%, respectively, in radionuclide left ventricular ejection fraction. The other toxicities were mild. In the 16 patients with squamous cell carcinoma that could be evaluated for response, one had a partial response lasting 8 months, and six had stable disease. One of the two patients with parotid adenoid cystic carcinoma had a minor response lasting 16 months. Mitoxantrone on a bolus schedule has minimal activity and is not indicated in head and neck squamous cell carcinoma.