Early embryonic death (EED) is one of the causes of infertility in the mare. We compared endometrial environment in 9 mares with EED and 13 mares in diestrus phase. Cotton swab (CS), cytobrush (CB) and uterine biopsy (B) samples were obtained for the cytological, bacteriological and histopathological examinations. In the first step we compared CS and CB methods to biopsy as a reference method, as B revealed the highest number of positive results in cytological and bacteriological examinations in both groups. In turn, we also compared cytological, bacteri- ological and histopathological findings between EED and control animals using the B sampling. Although the differences between these groups were not statistically significant (p≥0.05), there was a tendency to a higher prevalence of subclinical endometritis in the control group, than in the EED group (62% vs 22%). In general, positive bacteriological results were similar in both groups (62% vs 55%), whereas positive cytological results were higher in the control group (62% vs 22%; p≥0.05). In histopathological examination in EED mares endometrial degeneration was better expressed (all mares were with grades IIB and III on the Kenney-Doig scale); however, the differences between both groups were not statistically significant (p≥0.05). We could not confirm a clear difference in uterine environment between the two groups. Moreover, the uterine biopsy seemed to be the most reasonable sampling method for diagnosis of endometrial state.