Background and study aim:: Spontaneous bacterial peritonitis (SBP) is an important cause of morbidity and mortality in patients with cirrhosis and ascites. The diagnosis of SBP is established when the ascitic fluid polymorphonuclear leukocyte (PMN) counts is ≥250 cells/ mm3 with or without a positive ascitic fluid culture but this test lack sensitivity. The objective of this study was to evaluate the possible role of lactoferrin in diagnosis of SBP. Patients and methods:  The study included seventy patients with liver cirrhosis and ascites admitted to hospital. Patients were classified into SBP group and control group by ascetic fluid PMN count. Aspirated ascitic fluid samples were examined for bacteriological culture, biochemical assay, and cytological count. Ascitic fluid lactoferrin was measured by ELISA technique Results :Ascitic fluid lactoferrin was significantly increased in SBP patients compared to control group. There was a statistically significant positive correlation between lactoferrin levels and PMN counts in SBP patients (p<0.001). ROC curve was used to determine a cutoff value for lactoferrin in diagnosis of SBP. At lactoferrin level ≥270 ng/ml, the sensitivity was 96%, specificity was 95%, positive predictive value was 97.96%, negative predictive value was 90.5%, and accuracy was 95.7% in diagnosis of SBP. Conclusion : Measurement of ascitic fluid lactoferrin could serve as a rapid and reliable screening tool for diagnosis of SPB.