Survival data of the patients were correlated to tumour size, axillary lymph node (pN) status, mitotic frequency and morphometric prognostic index (MPI) in a series of 611 women with a primary breast carcinoma treated and followed-up for over 12 years in Kuopio University Hospital. The pN status, tumour size, mitotic activity index (MAI), volume-corrected mitotic index (M/V index) and MPI all predicted recurrence-free survival and cancer survival (p < 0.001). In pN(-) patients, the MPI was the most important predictor of recurrence-free survival and cancer survival (p < 0.001) followed by the mitotic frequency. In pN(+) patients, tumour diameter and MPI were equal predictors (p < 0.001) of survival followed by M/V index. In Cox's analysis, MPI, pN status and mitotic frequency independently predicted survival in the whole series. In the separate analysis of pN(-) and in pN(+) tumours, the MPI and MAI independently predicted survival. The M/V index was independently related to recurrence-free survival in pN(+) tumours. In multivariate analysis, MPI was an independent predictor although it does not include all the prognostic information. The results suggest that the decisions on adjuvant therapy in breast cancer can be based on the MPI, particularly in pN(-) patients.