Adjuvant tamoxifen (TAM) has been proved to reduce recurrence and mortality in early breast cancer, nevertheless many patients did not receive TAM as adjuvant therapy after local treatment. In order to study the efficacy of delayed TAM therapy in patients who were not given immediate adjuvant hormonal treatment, a multicenter randomized trial has been conducted by the French National Cancer Centers (FNCLCC). According to eligibility criterias all women with breast cancer who received curative local treatment at least 2 years before (surgery +/- radiotherapy) with or without adjuvant chemotherapy but no hormonal treatment could have been included. Between September 1986 and October 1989, 494 women were randomized to receive either TAM 30 mg/day for 5 years or no treatment. Patients' characteristics such as age, tumoral stage, number of positive nodes, receptors status and time from local treatment were equally distributed in the 2 groups. An improvement in the disease free survival in the TAM treated patients can be observed with a significative difference (p = 0.05), nevertheless the overall survival is not improved in the TAM group. In the same way, in nodes positive patients although no significative improvement in the overall survival can be observed, a significative improvement in the disease free survival (p = 0.05) can be noted. In estradiol receptors positive patients tamoxifen gives a significative reduction in the odds of death (p = 0.04) and recurrence (p = 0.03). The disease free improvement seems to be limited to 50 and more years old patients. The first results of this trial lead to prescribe tamoxifen to all postmenopausal women previously treated for an early breast cancer without adjuvant tamoxifen treatment.