Endometritis in dairy cow herds is a serious economic problem all over the world due to the large economic losses.Subclinical endometritis is an important postpartum disease in dairy cows, but conventional cytobrush diagnosis often gives imprecise results.Measuring inflammatory cytokine levels in serum from dairy cows with clinical or subclinical endometritis during the voluntary waiting period may provide valuable information that can serve as a diagnostic tool for the uterine inflammation.The objective of this study was to analysis disease-associated changes of inflammatory cytokines in serum as potential diagnostic parameters.The study was performed on 28 cows on day 30 after delivery.Based on the results of cytological tests, the cows were divided into three groups: clinical endometritis (10 cows);subclinical endometritis (6 cows);healthy control (12 cows).Clinical endometritis was diagnosed by observation of vaginal discharges (> 50% pus) and subclinical endometritis was diagnosed by evaluation of uterine flush cytology (neutrophils > 5.5%) at 4 weeks postpartum.Serum samples were obtained from 28 cows at 4 and 25 weeks postpartum for evaluation of tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) concentrations.Concentrations of CRP were greater (P<0.05) in cows with clinical endometritis than in cows with subclinical endometritis and healthy controls, whereas concentrations of TNF-α in both cows with clinical and subclinical endometritis were greater (P<0.005) than in healthy controls.In conclusion, cows with endometritis have greater inflammatory cytokine concentrations in serum than healthy cows,concentrations of TNF-α and CRP differences were observed.Subclinical endometritis of dairy cows is reflected by concentrations of TNF-α in serum.The data emphasize the role of TNF-α and CRP for bovine subclinical endometritis, and point the way for analysis of TNF-α as potential candidate parameter associated with subclinical endometritis.