Fine needle aspiration (FNA) is routine diagnostic tool in breast tumors assessment. In some cases, however, limitations of this method do not permit an unequivocal diagnosis. In these, suspected, cases immunocytochemical evaluation of selected biological markers may be of help. The aim of the study was assessment of HSP27 value in diagnosis and discrimination of benign and malignant breast lesions. HSP27 expression was examined by immunocytochemistry in fine needle aspiration smears assessed to C2-C5 categories. In C5 subgroup HSP27 expression was correlated with ER, PR content. Statistically significant differences in HSP27 expression between subsets C2/C5 and C3/C5 were found (p=0.028 and p=0,04, respectively); the differences between C3/C4 categories were not significant. Expression of HSP27 protein in FNA smears can be additional factor, which helps to differentiate benign, and malignant breast lesions, however it is not useful for discrimination of cytological, suspicious lesions.