The unfavorable morphological changes in the oviductal mucosa may lead to infertility in females and be one of the reasons for slaughtering of farm animals. The aim of study was to investigate the morphological changes in the epithelium of oviductal mucosa of sows with ovarian cysts. The oviducts of 18 sows were obtained after slaughter. Sows were divided into three groups: 1st group - 6 sows with polycystic ovaries, 2nd group - 6 sows with single cysts, 3rd group - 6 sows without ovarian cysts. The epithelium was examined by light microscopy, SEM and TEM. Ciliated and secretory cells were count on 150 Îźm segments in apical and basal zone of folds both in ampulla and isthmus. We analyzed the number of cells in 5 folds in both these oviductal parts in dexter and sinister oviduct. We have noted unfavorable changes in oviductal mucosa consisting in increase of the secretory cells with simultaneous decrease of ciliated cells. The correlations between the general occurrence of ovarian cysts and the morphological state of epithelium of oviductal tunica mucosa were determined. The changes in proportion of cells occurred both in ampulla and isthmus. The excessive secretion covering epithelium promotes agglutinations and adhesions of the tubal folds and occlusion of the oviduct. These alterations may create problems in the migration of gametes and prevent the movements of the zygote towards the uterus and cause some disturbances in conceptus development in its early stages. Results suggest that COD is connected with unfavorable morphological and functional changes within epithelium of the oviductal tunica mucosa.