Spontaneous bacterial peritonitis (SBP) is a prototypical infectious disease of cirrhotic patients. It has been suggested that cirrhotic patients' response to infection is less effective because of differences in the inflammatory and immune reactions. This study aimed to investigate the expression of the inflammatory cytokines monocyte chemotactic protein-1 (MCP-1) and interleukin-10 (IL-10) in cirrhotic patients with SBP. The MCP1 and IL-10 levels in the sera and ascitic fluids of cirrhotic patients with (n = 40) or without SBP (n=17) were serially analyzed by ELISA. In the non-SBP group, the mean MCP-1 levels in sera and ascites were 53.0 +/- 45.8 pg/mL and 197.5 +/- 109.5 pg/mL, respectively, and the IL-10 levels were 10.9 +/- 9.5 pg/mL and 77.6 +/- 79.7 pg/mL, respectively. In the SBP group, the mean MCP-1 levels in serum and ascites before treatment were 164.7 +/- 126.4 pg/mL and 365.3 +/- 583.0 pg/mL, respectively, and the IL-10 levels were 31.4 +/- 44.1 pg/mL and 188.1 +/- 189.5 pg/mL, respectively. The sera MCP-1 and ascites IL-10 levels differed significantly between the two groups. In the SBP group, sera and ascitic MCP-1 and IL-10 levels fell during treatment. The low MCP-1 and IL-10 levels on the seventh day of treatment were found to have a statistically significant relationship to patient survival. MCP-1 and IL-10 levels in sera and ascites may be related to the clinical course of SBP.