Spontaneous bacterial peritonitis (SBP) is a severe complication in cirrhotics with ascites. Monocyte chemotactic protien-1 (MCP-1) is a chemotactic factor for monocytes/macrophages, and it activates lymphocytes and neutrophils during infection. This study aimed to evaluate the role of MPC-1 in the pathogenesis of SBP and assess its prognostic value and correlation to disease severity. The study included ninety patients with liver cirrhosis and ascites. Patients were divided into 2 groups: Group I including 45 ascetic patients with SBP (polymorph nuclear cell count (PMN) ≥ 250 cell/mm3 in ascitic fluid), and Group II including 45 ascetic patients without SBP. Assessment of the severity of liver cirrhosis was done using the modified Child-Pugh and model for end stage liver disease (MELD) scores. Ascetic fluid samples were subjected to total leucocytic count and differential, albumin, protein, glucose, and serum-ascetic albumin gradient analysis Ascetic fluid levels of (MCP-1was measured by ELISA. Higher level was detected in patients with SBP as compared to those without SBP. The number of polymorph nuclear cell count (PMN) ≥ 250 cell/mm3 in ascitic fluid) was used as gold standard for diagnosis of SBP. The diagnosis sensitivity and specificity of MCP level test were 86.7% and 95.4% respectively at cutoff of122.5ng/ml with accuracy 91%. MCP-1 level showed positive significant correlation with TLC, PMN leucocytes and MELD score. In conclusion, ascitic fluid MCP-1 level could be a reliable test for diagnosis of SBP, and could be used as a prognostic marker due to its positive correlation with the severity of liver disease.