BACKGROUNDThe sensitivity for identification of malignant cells in conventional fine-needle aspiration biopsy (FNAB) investigation is about 80%. This percentage is dependent on the number of examined cells, type of breast cancer, and experience of the examiner. The aim of our study was to estimate the supporting value of image DNA cytometry of FNAB of the breast, and do so by using different sampling methods.MATERIALS AND METHODSThis retrospective study was based on 41 cases with an available histological diagnosis: 18 benign lesions and 23 malignant tumours were examined. The smears were submitted to image DNA analysis in a three-step protocol: (i) smears stained with HE method were destained and (ii) then restained with Feulgen staining for DNA and (iii) finally analysed using image cytometry.RESULTSAll non-malignant cases had diploid histogram. However, a few of them had one or two cells of >5c category. Most histologically malignant cases were aneuploid. Only three invasive ductal carcinomas showed diploid histograms. All samples with aneuploid histograms were malignant.CONCLUSIONThe results confirm earlier published data in the Finnish population and indicate that image DNA cytometric analysis of nuclear content is a useful marker for identification of malignant cells in FNAB, especially after free cell sampling. The method can be used to increase the cytological sensitivity and specificity in doubtful breast lesions.