Abstract: To explore the clinical significance of plasma and ascitic procalcitonin (PCT) levels in cirrhotic patients with spontaneous bacterial peritonitis (SB) . Plasma and ascitic PCT levels in 62 ascitic patients (SBP 41 and non SBP 21) were detected by immunoluminometric assay, and compared with TNF-α、IL-6 levels. Plasma and ascitic PCT、TNF-α and IL-6 levels were significantly higher in SBP group than that in non SBP group (P<0.01) . In diagnosis of SBP, the positive predictive value (non SBP group x+2SD as the cutoff value) was the highest by plasma PCT than by the others, while the highest negative predictive value was ascitic IL-6. Plasma PCT、TNF-α and IL-6 levels in the death at admission were significantly higher than that in the survivals at the same time, but no in ascitic fluid. Plasma PCT level can be used as a useful indicator to the diagnosis and prognosis in cirrhotic patients with SBP.