The prognosis of young breast cancer patients has been considered to be much poorer than in older patients. Two hundred and sixty-eight premenopausal women with a median follow-up time of 74.0 months were included in the study. 33.5% had oestrogen receptor-negative and 34.6% progesterone receptor-negative tumours. 15.2% of the tumours were HER2-positive. Five-year breast cancer-specific survival (BCSS) was 81.1% and the corresponding 10-year figure was 72.3%. 91.8% of all relapses occurred within seven years of surgery. Among the