The aim of the study was to examine the consecutive series of primary ductal invasive tumours and find out: a) the expression of some biological cellular parameters as proliferating antigens Ki67 and PCNA and products of gene EGFR, erbB2; b) correlation between the levels of expression of those factors and classical prognostic factors, such as diameter of tumour, status of axillary lymph nodes, status of steroids receptors, the degree of histological differentiation. We found that: 1. The presence of the expression of oncoproteins c-erbB2 and EGFR, high index IP PCNA, Ki67 and low levels of steroids receptors correlates with high histological malignancy (Bloom III0); 2. The lack of expression of oncoproteins c-erbB2, EGFR and low index IP PCNA, Ki67 correlates with high levels of steroids receptors; 3. The estimation of high levels of index IP PCNA, IP Ki67 can be helpful for separate tumours of high proliferating activity; 4. The expression of oncoprotein c-erbB2 and EGFR does not correlate with the diameter of tumour as well as with the involvement of axillary lymph nodes. It seems that the estimation of proliferating antigens together with the expression of oncoproteins might have greater prognostic value than the estimation of one of these factors.