Endometritis is frequently encountered in brood mare practice and is one of the main causes of infertility. Several methods, including among others cytology. bacteriology and histopathology, are used for diagnosis, however, even the combined use of these methods may not produce a definitive result. The objective of this study was to make an assessment of the diagnostic efficiency of centrifuged liquid-based cytology (LBC) in comparison to the determination of: 1) the presence of polymorphonuclear cells (PMNs) in the uterine epithelium and stratum compactum by histopathology; 2) the presence of PMNs by cytology and 3) the presence of uterine infection by microbiology. Fifty mares of varying age, which belonged to the Jockey Club of Turkey, were used in this study. Endometrial samples were harvested using the cytobrush (CB) and endometrial biopsy (EB) techniques for microbiological, Cytological and histopathological examinations. The comparison of liquid-based cytology (LBC) with histopathological diagnosis (HD), which is considered to be the best standard, showed that the sensitivity (SE), specificity (SP), predictive value of positive test (PVP), and predictive value of negative test (PVN) of LBC were 0.5000, 0.4000, 0.7692 and 0.6087, respectively. No coherence was detected between the results of these two methods (P = 0.0166). Furthermore, it was ascertained that LBC failed in detecting degenerative and fibrotic alterations in the endometrial glands. LBC slides provide sharp images of well-dispersed cells, and enable greater diagnostic sensitivity and certainty. Thus. as the area examined is small, the identification of the target cells is relatively easy.