A total of 25 patients with metastatic renal cancer were treated on a phase II protocol with 5 days of continuous-infusion fluorodeoxyuridine (FUDR), (0.1 mg/kg daily) together with high-dose oral leucovorin (100 mg 4 h) and daily x6 high-dose interferon-alpha 2b (30 x 10(6) IU/m2). Despite the good performance status of the patients and the inclusion of 14 previously untreated patients in the cohort, no response was observed among the 20 evaluable patients. Toxicities included high fever, moderate anemia, transient leukopenia, transient and mild elevations of transaminases, and moderate to severe nausea, vomiting, diarrhea, and mucositis. There were also two episodes each of confusion, fluid retention, and pancreatitis and one episode of increased creatinine levels. During the study three deaths occurred, two of which were possibly therapy-related. Despite previous reports of activity of FUDR in metastatic renal cancer, the present regimen cannot be recommended.