The Scarff-Bloom-Richardson (SBR) multiparametric histological grading has been correlated with the immunohistochemical expression of EGF-R, c-erbB-2 and p53 oncoproteins, with the growth fraction (Ki67 antibody) and with the receptor status (ER, PgR) in 365 infiltrating ductal carcinomas of the breast (IDC-NOS). Specimens of carcinomas after surgery were sectioned and a section of each lesion was formalin-fixed and paraffin-embedded, and stained by hematoxylin-eosin in order to classify and grade cases. Another section was liquid nitrogen frozen, cryostatcut and immunostained using monoclonal antibodies against EGF-R (455 and 528 clones), c-erbB-2 (3B5 clone), p53 (Pab 1801 clone) and Ki67 antigen. An ABC-peroxidase was used after incubation with biotinylated antimouse antibody. Colour was developed using a DAB solution. ER-ICA and PgR-ICA Kits (Abbott) served to detect the hormonal receptor status. A significant direct correlation between SBR and the immuno-histochemical markers (EGF-R, c-erbB-2, p53, Ki67 growth fraction) was found. An inverse relationship of grade to ER and a weaker one to PgR was evident. An increasing histological grade was found parallel with the progressive appearance of one, two or three immunohistochemical markers in the same tumour.