Alterations of gap junctional intercellular communication appear to play a role in the development and progression of cancer. Gap junction channel is composed of two connexons - hexameric units formed of transmembrane proteins called connexins (Cxs). The aim of the study was to evaluate the expression and localization of Cx26 in 73 cases of endometrial cancers and to estimate the relationships between expression of this protein and selected anatomoclinical features. The control group consisted of 20 sections of normal endometrium in various menstrual cycle phases, obtained from premenopausal women. In the normal endometrium punctate, membrane-associated immunoreactivity for Cx26 was observed. 54 of 73 endometrial cancers showed Cx26 expression, but 46/54 (85%) immunopositive sections revealed cytoplasmic localization for Cx26 with granular or occasionally diffuse immunostaining pattern. In addition, part of Cx26-positive tumours showed mixed: cytoplasmic and membranous staining pattern and focally also nuclear or perinuclear immunostaining was present. In 21/54 (39%) of Cx26-positive cases weak staining pattern was seen, however in 33/54 (61%) cancers strong reaction was noted. We did not find relationship between Cx26 expression and patients' age, histological type of cancer and histological grade, nevertheless we observed positive association between Cx26 expression and tumour size (p=0.037). In conclusion, our results suggest that transformed malignant cells continue to produce Cx26, which are probably not assembled into functional gap junction channels, but could still play other roles in endometrial cancer cells.