ObjectiveTo evaluate the significance of procalcitonin(PCT) test in guiding antimicrobial therapy in patients with liver cirrhosis ascites.MethodsOne hundred patients with liver cirrhosis ascites in a hospital between January 2009 and January 2012 were randomly divided into routine therapy group(routine comprehensive therapy, n=20) and antiinfective therapy group(cefotaxime therapy in addition to routine therapy, n=80),then antiinfective group was subdivided into antiinfective group A（PCT＜0.5 ng/mL）, antiinfective group B（0.5 ng/mL≤PCT≤2 ng/mL）and antiinfective group C（PCT＞2 ng/mL）.Liver function, prothrombin activity （PTA）and therapeutic efficacy between three groups were compared.ResultsAfter therapy, the difference in serum alanine transaminase（ALT）, aspartic transaminase（AST）,total bilirubin（TBIL）,and PTA between antiinfective group A and routine therapy group were not significantly different(all P＞0.05);compared with antiinfective group A and routine therapy group, ALT,AST and TBIL in antiinfective group B and C decreased significantly, while PTA increased significantly (all P＜0.05）. The total efficacy rate in routine therapy group, antiinfective group A, B and C was 60.00%（12/20）,66.67%（18/27）,87.50%（28/32）,and 90.48%（19/21），respectively（χ2=9.04，P=0.03）, the total efficacy rate in antiinfective group B and C increased significantly.ConclusionDetection of PCT is benefit to judge the development of bacterial peritonitis in patients with liver cirrhosis ascites and guide rational use of antimicrobial agents.