Gonadotrophin-releasing hormone analogues were investigated as adjuvant treatment for patients with node-negative, hormone-sensitive, premenopausal breast cancer. Patients were randomised to either three cycles of cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) chemotherapy (n=378) or goserelin every 28 d for 2 years (n=393). During a median follow-up of 4.9 years, 123 events were observed. The first-failure event of CMF versus goserelin, respectively, was ipsilateral locoregional recurrence (18 versus 20), contralateral breast cancer (7 versus 6), distant failure (35 versus 24) and death without recurrence (2 versus 2). Forty-two (23 versus 19) deaths of any cause occurred. The estimated adjusted hazard ratio for goserelin versus CMF (intention-to-treat analysis) was 0.79 (95% CI=0.54-1.14; P=0.19). It is concluded that medical ovarian ablation with goserelin represents a valid option for premenopausal patients with node-negative breast cancer.