In this study, patients with operable breast cancer T2 or T3, treated by mastectomy + axillary dissection and with invaded axillary nodes (N+), were randomized to receive either: 1) postoperative locoregional and pelvic radiotherapy (RX) and Poly(A).Poly(U) (AU), 60 mg IV once a week for 6 weeks, or 2) CMF (cyclophosphamide 100 mg/sqm P.O. on days 1-14, methotrexate 40 mg/sqm IV on day 1 and 8, fluorouracil 600 mg/sqm IV on day 1 and 8; monthly cycle, for 6 months. Between March 1982 and December 1985, 517 patients were enrolled, 257 of whom were treated by RX + AU and 260 with CMF. The main clinical, pathological and prognostic characteristics were equally distributed in the two groups. The present analysis was conducted after a mean follow-up of 69 months (S.D. = 13). There was no significant difference in overall survival (OS) between the two groups (test adjusted by center and menopausal status); the five-year OS rate was 74% in the RXAU group and 77% in the CMF group. Relapse-free survival (RFS) was significantly higher (p = 0.05) in the RXAU group compared to the MCF group; the five-year RFS rates were 57% and 46% in the two groups respectively. This short, well-tolerated combined RXAU treatment appears to be as efficient as CMF and might offer an alternative to chemo- or hormonotherapy, in case of contraindications to these treatments.