Survival data of a cohort of 160 patients with breast cancer, who were still alive 10 years after the primary diagnosis, and who had been followed up for at least 22 years, were investigated to find out those factors that predict late mortality from breast cancer. The 13 factors investigated included age at diagnosis, histological type and grade, mitotic count, type of tumour margin, inflammatory cell reaction, extent of tumour necrosis, primary tumour size, axillary nodal status, DNA ploidy and index, S-phase fraction and occurrence of a second primary breast cancer. Advanced age at diagnosis (greater than 49 years, P = 0.002), occurrence of a second primary breast cancer during the follow-up (P = 0.01), and primary tumour size (T3-4, P = 0.03) were significantly associated with mortality from breast cancer after the 10th year of follow-up in a multivariate analysis, and the ductal invasive histological type (P = 0.03) and a large DNA index (greater than 1.2; P = 0.06) in univariate analyses.