Amonafide (nafidimide), a synthetic organic compound with an inhibitory effect on cellular replication, was used in a phase II study conducted by the Illinois Cancer Center in order to assess its efficacy and toxicity in advanced or recurrent squamous cell cancer of the head and neck. Eligible patients had received no more than one prior adjuvant or neoadjuvant chemotherapy, had normal bone marrow, renal and hepatic function, ECOG performance status of 0-2, and bidimensionally measurable disease. Eligible patients were administered amonafide at a starting dose of 300 mg/m2 for five consecutive days every 3 weeks with dose escalation or de-escalation according to established hematologic criteria in the absence of disease progression. Nineteen of 22 entered patients were evaluable for response and all patients were evaluable for toxicity. Eleven of 19 patients achieved stable disease. Median time to progression after start of treatment was 57 days, for the 18 patients for whom the date of progression is known. There were no partial or complete responses. Hematologic toxicity was dose limiting with grade 3-4 neutropenia in 50 percent of patients and 4 deaths associated with neutropenic sepsis. Non-hematologic toxicity was mild to moderate with nausea and vomiting predominating. In this study, amonafide was a myelotoxic, inactive treatment in advanced/recurrent head and neck cancer. Further use in head and neck cancer appears unwarranted.