DNA nuclear content was assessed in human breast carcinomas (n = 132) using image cytometry. Optical density histograms of Feulgen stained cell imprints from fresh tissue samples, subsequently frozen for immunocytochemical assays, were determined by the SAMBA system and used for the DNA index, the ploidy balance (PB) and the proliferation index (PI) computation. The three parameters were correlated to (i) histological data (tumour grade, vascular and/or lymph node invasion) and to (ii) growth fraction (Ki67), hormone receptor antigenic sites (ER, PR) and intramedullar (bone marrow) biopsies and anti-KL1-positive epithelial cells. It was shown that 57% of breast carcinomas were aneuploid. Aneuploidy PI significantly correlated to the criteria of poor prognosis such as high tumour grade, vascular and lymphatic invasion and to increased Ki67-positive cells, and the absence of or low ER and PR. Since image cytometry is easy to handle and perfectly suitable for current diagnostic practice in pathology departments, particularly for tumour cell ploidy assessment and standardized analysis of immunostaining procedures with morphological control of the preparation, we conclude that image cytometry, as performed with the SAMBA, must be regarded as a relevant tool for prognosis evaluation and therapy guidance in individual patients.