Necrotizing enterocolitis (NEC) is the most common neonatal gastrointestinal emergency, predominantly affecting low-birth weight, premature infants. Early clinical signs of NEC are nonspecific and the laboratory findings are not fully reliable. Its severe morbidities and rapid progression require the application of new biomarkers for early diagnosis and intervention. The complement activation product, C5a (anaphylatoxin) has been reported to be a contributing factor leading to mesenteric ischemia/reperfusion injury which is a predisposing factor in the pathogenesis of NEC. Therefore, our aim was to evaluate the efficacy of serial C5a measurements in the diagnosis and follow-up of NEC. Preterm infants, whose gestational age and weight matched each other, were grouped as controls (n = 23) and NEC (n = 22). Serum levels of C5a, serum amyloid-A (SAA), C-reactive protein (CRP), and interleukin-6 (IL-6) levels were measured on the third day of life for the control group and on the day of diagnosis (1st day), 3rd and 7th days of the NEC group. C5a, SSA, CRP, and IL-6 levels were significantly higher in the NEC patients compared to the control group (P < 0. 05) in the follow-up. Additionally, serum levels of C5a were found to be more accurate than the other parameters for the prediction of death and requirement for surgery at the time of diagnosis (P < 0. 05). In conclusion, C5a may be useful as a new marker for both diagnosis and follow-up of infants with NEC in combination with clinical and radiographical findings VSports手机版. .