The prognostic value of Ki-67, p53 and ER immunohistochemical labelling and flow-cytometric S-phase fraction and ploidy was evaluated in 212 pT1N0M0 breast carcinomas. The mean follow-up time was 8.3 years. Patients with breast carcinomas with high Ki-67 expression (> or = 10%) had a less favourable disease-free survival than those with low Ki-67 expression (< 10%) (p = 0.008). A positive p53 staining and high SPF were associated with a less favourable disease-free survival although it did not reach statistical significance. The subset of patients with ER negative, Ki-67 > or = 10% and p53 > or = 20% tumours, had a shorter disease-free survival compared with that of all the other patients (p = 0.03). We conclude that the potential value of Ki-67 labelling for prognostic evaluation of T1N0M0 breast carcinoma is good.