Between 1989 and 1993, 409 evaluable patients with breast cancer have been treated with tegafur and uracil (UFT) in an adjuvant setting in two different trials. Data from both trials were reviewed in December 1995 after a mean follow-up of 5.09 +/- 1.1 years (range, 2.9 to 7.1 years). The aim of the first trial was to demonstrate the activity of UFT 400 mg/day for 6 months plus prednimustine 60 mg/m2 for 7 consecutive days, every 28 days in 6 cycles given orally (arm B). This scheme was compared with 6 cycles of cyclophosphamide 600 mg/m2, plus methotrexate 40 mg/m2, plus fluorouracil 600 mg/m2, every 4 weeks (arm A). In this study, 187 premenopausal women were evaluable, 96 in arm A and 91 in arm B, all of whom had positive axillary nodes. Although there were more younger patients in arm A than in arm B, prognostic factors were similar in both groups. Disease-free survival and overall survival were similar in both arms. However, some concern is raised by the low disease-free survival rate. The toxicity was mild (mainly nausea and vomiting and alopecia) and slightly worse in arm A. We believe that oral administration could be a useful alternative to the parenteral route. In the second trial, 222 evaluable patients received 20 mg/day of tamoxifen (Nolvadex) for 1 year (arm A), or the same dose of tamoxifen plus UFT 400 mg/day for 6 months. All patients were postmenopausal, and the characteristics of the tumors were the same as those in patients in the first trial. In arm A there were 109 patients and in arm B, 113. The groups were well balanced. The overall survival and the disease-free survival rates were equal in both arms, but were longer in arm B in the subset of patients with five or more axillary-involved nodes. The toxicity was negligible in both arms. We conclude that UFT/tamoxifen might be useful in postmenopausal patients with five or more involved nodes who are unable to follow a more aggressive schedule because of their age or low performance status.