Cytologic specimens (FNA) from 42 primary invasive ductal breast carcinomas and 22 matched specimens of cancer tissue were tested for EGFR status, PCNA index and vimentin expression by immunocytochemical staining, using an Extravidin-Biotin method, and their relationship with various prognostic factors was investigated. EGFR positivity, high PC10 score and vimentin positivity were significantly correlated with high histologic grade. The coordinate expression of EGFR, PCNA and vimentin was significantly associated with ER-negative breast carcinomas. A positive trend was observed between high proliferating tumours and EGFR expression. EGFR status and PCNA index were not correlated with axillary lymph node involvement, tumour size, age and menopausal status. Vimentin was preferentially expressed in tumours, with lymph node metastases. Co-expression of EGFR, PCNA and vimentin was determined in most cases. These data suggest that EGFR status, PCNA index and vimentin expression may be important for the prediction of biologically aggressive tumours.