This phase II study evaluated docetaxel-5-fluorouracil (5-FU) in locally recurrent and/or metastatic squamous cell carcinoma of the head and neck (SCCHN). Patients were divided into 2 cohorts--those previously treated with chemotherapy and those nonpretreated--that received docetaxel 75 mg/m2 (day 1) plus 5-FU 1,000 mg/m2/day (days 1-5 every 3 weeks). Of 63 patients entered, 20 (31.7%) were pretreated and 43 (68.3%) were nonpretreated. Fifty-nine patients (93.7%) had received prior radiotherapy. After inclusion of 20 patients, the 5-FU dose was reduced to 750 mg/m2/day due to unacceptable toxicity. The overall response rate (ORR) was 20.6% on radiologic review (22.2%, investigator assessment). Pretreated patients achieved an ORR of 25.0% versus 18.6% for nonpretreated patients. This unexpected finding was partly attributed to differences in patient characteristics between the groups. Overall major grade 3 to 4 toxicities comprised neutropenia (66.6%), febrile neutropenia (31.7%), and mucositis (31.7%). Grade 3 to 4 toxicities were lower at the reduced 5-FU dose (750 mg/m2/day): Febrile neutropenia declined from 40.0% to 27.9%; mucositis declined from 55.0% to 20.9%. Three treatment-related deaths occurred (2 with 5-FU 750 mg/m2/day, 1 with 5-FU 1,000 mg/m2/day). Docetaxel-5-FU appears active in locally recurrent and/or metastatic SCCHN with acceptable toxicity at the dose of 5-FU 750 mg/m2.