Background: Liver cirrhosis represents one of the major causes of death worldwide. Many complications can be de-tected in liver cirrhosis. Among these complications is ascites which seems to be the most frequent one. Patients with cirrhosis and ascites show a higher susceptibility to bacterial infections mainly because of the inadequate defense mecha-nisms. In those patients, the most frequent infectious compli-cation that occurs and at the same time the most severe one is spontaneous bacterial peritonitis.Aim of Study: To identify the frequency of spontaneous bacterial peritonitis in patients of liver cirrhosis with ascites at Tanta University Hospitals.Patients and Methods: This study included three hundred patients with liver cirrhosis and ascites. Data were collected including; clinical, demographic and laboratory data. Ascitic fluid analysis and/or culture were done for diagnosis of SBP. Statistical analysis was carried out for all collected data using IBM & SPSS Version 20. Statistical significance was deter-mined at a p-value <0.05.Results: The frequency of spontaneous bacterial peritonitis in patients of liver cirrhosis with ascites at Tanta University Hospitals represented by 41.7%.Conclusions: The frequency of spontaneous bacterial peritonitis in patients of liver cirrhosis with ascites at Tanta University Hospitals represented by 41.7% of the collected cases.