The aim of the current study was to compare between different regimens used for treatment of endometritis in mares with the help of ultrasonography. This study was carried out on 50 repeat breeding mares (35 mares with endometritis and 15 mares (control group) without endometritis). All mares were examined by trans-rectal ultrasonography and uterine swabs were obtained for laboratory diagnosis and sensitivity testing. Mares with endometritis were divided into three groups according the type of treatment; group (1) contains 12 mares were treated by I/V infusion of Enrofloxacin  once daily for 5 days and I/M injection of  25 IU oxytocin, group (2) contains 12 mares were treated by uterine wash with normal saline for 3 days and I/M injection of 25 IU oxytocin, group (3) contains 11 mares were treated by uterine wash with normal saline and Gentamicin for 3 days and I/M injection of 25 IU oxytocin. The results revealed that uterine horn diameter was significantly larger (p < 0.05) in repeat breeding mares with endometritis (7.28 cm) than that in control (5.18 cm). The best recovery rate was obtained after using Enrofloxacin for 5 days with oxytocin, where (8/12, 66.7 %) mares became pregnant, followed by uterine wash with saline and Gentamicin for 3 days and I/M injection of 25 IU oxytocin, where (6/11, 54.5 %) mares became pregnant and finally uterine wash with saline for 3 days and I/M injection of 25 IU oxytocin, where (4/12, 33.3 %) mares became pregnant. Moreover, ultrasonography is an essential tool for diagnosis of endometritis in mares, Enrofloxacin together with uterine ecbolic as a treatment improved pregnancy rate of affected mares and Enrofloxacin may be an appropriate option for treatment of infectious endometritis associated with susceptible bacterial infection in mares.