Objective To assess the application value of serum procalcitonin(PCT)for the differentiation between the neonates with or without septicemia.Methods PCT,C-reactive protein(CRP),blood and blood culture tests were done in 75 cases of neonatal septicemia as the therapy group,and 74 neonates without the signs of infection as the control group after the admission of our hospital One week later,the therapy group also re-examined the PTC and CRP tests.Furthermore,the results were analyzed.Results The levels of CRP(23.26±5.68)mg/L and PCT(7.61±4.53)ng/L in therapy group were dramatically reduced compared with(4.09±1.09)mg/L,(1.95±0.25)ng/L in therapy group,and(6.42±4.54)mg/L,(0.45±0.16)ng/L in the control group before therapy,the t values are 28.71,12.97 and 19.97,14.08 respectively,and p value are both less than 0.01.The positive rates of PTC,CRP and blood culture were 82.7％,48.0％ 28.0％ before the admition to hospital.The differences of PTC and CRP,PTC and blood culture had statistical significances(x2=5.64,P＜0.05;x2=10.40,P＜0.01).If 2.5 μg/L of PCT and 8mg/L of CRP would be regarded as cutoff point in our study,the sensitivity and specificity of PCT or CRP for diagnosis of neonatal septicemia was 82.7％ and 80.3％,48.7％ and 78.4％.Conclusion Our data suggested that the serum PTC is a valuable marker for the early diagnosis of neonatal septicemia.