PURPOSE To assess the prevalence of spontaneous bacterial peritonitis (SBP) in asymptomatic patients with decompensated liver cirrhosis. MATERIAL AND METHODS Patients (pts) with symptoms of decompensation of liver cirrhosis, ascites, and no signs indicating SBP were included to our study. Exclusion criteria include: 1/ clinical symptoms of infection, 2/ developing de novo or worsening hepatic encephalopathy, 3/ gastrointestinal bleeding within the last month, 4/ renal failure, 5/ antibiotic treatment or norfloxacin prophylaxis at admission. About 60 ml of ascitic fluid were drawn for lab examination. Pathologic assessment for atypical cells was also performed. RESULTS 37 patients fulfilled inclusion criteria. Their mean age was 56.2 ± 12.1. The Child-Pugh classification revealed 13 (35.1%) patients of class B and 24 (64.9%) patients of class C. The mean Model for End-Stage Liver Disease score in this group was 16.6 ± 6.8. The mean ascitic protein content was 1.85 ± 1.09 g/dL and mean neutrophil count 144.8 ± 445.1/mm3. Ascitic fluid analysis revealed: signs of bacterascites in 6 of 37 (16.2%) pts; neutrocytic ascites in 1 of 37 (2.7%) pts; and 2 of 37 (5.4%) pts met criteria for SBP. C-reactive protein level was the best predictor of infection [SBP(+) 47.9 ± 40.9 versus SBP(-) 11.7 ± 5.1; p= 0.0005]. CONCLUSIONS The prevalence of SBP in asymptomatic cirrhotics with ascites is low. We observed the trend towards more frequent occurrence of the infection in patients suffered from severe liver disease (Child-Pugh C group).