Unlike cervical cytology, morphological cytology criteria in the differential diagnosis of endometrium have not yet been clearly defined, and methods to allow for more precise evaluation of endometrium status have been searched for. The aim of the present study was to assess the value of morphometric nucleus analysis of cytologic aspirate endometrial samples in proliferative, hyperplastic and malignant endometrium by use of digital image analysis. Morphometric analysis was performed on archival cytologic aspirate endometrial samples (at least 10 per group) stained according to Papanicolaou (n = 77) and May-Grünwald-Giemsa (MGG; n = 80) with the following histopathologic diagnoses: proliferative endometrium, hyperplasia simplex, hyperplasia complex, hyperplasia complex atypica, and adenocarcinoma endometriodes endometrii (grade I, II and III). Interactive image analysis (nuclear area, convex area, perimeter, maximum and minimum radius, length and breadth, as well as nucleus form factor and elongation factor) was performed by use of the SFORM software (VAMSTEC, Zagreb) on at least 50 (Papanicolaou stain) and 100 (MGG stain) well preserved endometrial epithelial cell nuclei without overlapping, at magnification of x1000. Statistical data analysis was done by use of the Statistica Ver. 6 statistical package. Multivariate analysis (ANOVA) distinguished malignant, hyperplastic and proliferative endometrium according to all morphometric variables with both staining methods (p < 0.05). However, on interactive testing of the groups (Kruskal-Wallis test), hyperplasias without atypia yielded no significant differences (p > 0.05) from atypical hyperplasia, adenocarcinoma and proliferative endometrium only according to the nucleus form factor and elongation factor (Papanicolaou stain), whereas malignant and atypical hyperplastic endometrium (MGG stain) differed statistically significantly (p < 0.05) from proliferative and hyperplastic endometrium without atypia according to all study parameters except for the nucleus form factor (p > 0.05). According to the cytologic staining method, morphometric parameters were considerably higher in MGG stained endometrial samples, reaching the level of statistical significance (p < 0.05) except for the nucleus form factor and elongation factor (p > 0.05) in the groups of hyperplasia simplex and complex, well differentiated adenocarcinoma (form factor) and atypical hyperplasia (elongation factor). A combination of cytomorphology and the morphometric variables assessed in this study can yield useful information on the cytologic state of endometrium, with special reference to the possible differentiation of the group of hyperplasia without atypia from the group of adenocarcinoma and atypical hyperplasia.