Subclinical endometritis is a physiological inflammation that serves to clear persistent contaminants from the uterus. To investigate the alteration of antioxidant, such as vitamin E (VE) and vitamin C (VC), total oxidant capacity (TOC) and nitric oxide (NO) in cows with normal and subclinical endometritis (SCE), we examined the concentrations of NO, VC and VE, TOC and polymorphonuclear neutrophils (PMN) percentage in uterine secretion. The cows were divided into two groups, normal (n=20) and subclinical endometritis (SCE,n=60), based on endometrial cytology (presence of PMN≥5%). Uterine secretion and blood were collected as described previously. Griess reaction was used to determine the concentration of NO. The concentrations of TOC, VC and VE were detected by a commercially available assay kit. The results showed that the concentrations of NO, TOC and PMN percentage were significantly higher (P<0.01,P<0.05, andP<0.01, respectively) in uterine secretion with SCE compared to those from normal;however, the levels of VC and VE were significantly lesser (P<0.01). In conclusion, the concentrations of NO, TOC, VC, VE and PMN percentage differed between normal and SCE cows. Meanwhile, the relationship between the concentration of NO and PMN percentage from uterine secretion in cows with subclinical endometritis were positively correlated. Consequently, these alterations in NO, TOC, VC, VE levels and PMN percentage contributed to as a diagnostic index of the uterine inflammation, with the aim to increase the reproduction of the cows and the decrease economic losses.