This study aimed to assess the reliability of various approaches for the diagnosis and management of endometritis in Arabian mares. Mares were subjected to a body condition score, perineal conformation, an ultrasonography examination, collection of uterine swabs and low-volume lavage swabs as well as endometrial biopsy. Mares were randomly selected for three different intrauterine treatment regimens and were serviced in the next estrus after the treatment. Results indicated that the proportion of abnormal vulval conformation increased as the age of the animals increased, along with a low body score. Bacteria and fungi were isolated from 83.64% of mares. Direct swabs were positively coincident in 36% with low-volume uterine lavage. Bacteriological and ultrasonography examinations contradicted in 71% of the cases (P < 0.05), while bacteriological and biopsy findings matched in 86.2% (P < 0.05). Swabs from low-volume lavage were more reliable than direct swabs in the diagnosis of endometritis. Cytological findings agreed with ultrasonography examination, while ultrasonography findings disagreed with biopsy grade in endometritis diagnosis (P < 0.05). Conception rates of mares treated with an intrauterine infusion of penicillin + gentamicin, ceftiofur, and cephapirin were 75%, 50%, and 28.6%, respectively. In conclusion, cytological and bacteriological assessment of the endometrium and an ultrasonography examination could be used with a high degree of confidence to diagnose endometritis in mares without the need for an endometrial biopsy. Although there is a low conception rate with one intrauterine infusion of cephapirin, it could be used successfully as a one-time intrauterine therapy in mares with endometritis.