Background: Spontaneous bacterial peritonitis (SBP) is the most common infection and a lethal complication in patients with liver cirrhosis and ascites. It has high mortality and recurrence rates and poor long-term prognosis. Objective: This study was done to determine the prevalence of spontaneous bacterial peritonitis and its variants in patients of liver cirrhosis with ascites. Patients and Methods: This was a prospective, randomized, cross-sectional clinical study, included 100 adult patients of decompensated liver cirrhosis with ascites in Aswan University Hospital during the period from January 2019 to December 2019. Results: Diagnosis of SBP is based on ascitic fluid analysis as well as culture and sensitivity. The diagnostic criteria are PMNL > 250/mm³ and or positive culture. Mean of age of patients was 63.06 ± 9.67 years old. Majority of patients were males (63%) and 37 % were females. In Our study, 62% of patients were diagnosed SBP. Classic SBP in 30.6%, Culture Negative Neutrocytic Ascites (CNNA) in 59.7% and MNB in 9.7% of patients. Of 25 patients who have positive culture ascetic fluid, 60% were positive for gram-negative bacteria predominantly E. coli. Conclusion: Spontaneous Bacteria Peritonitis is the most common and life-threatening infection in patients who have liver cirrhosis and ascites. It is diagnosed by a) Ascitic fluid PMNL > 250/mm³. b) Positive ascetic fluid culture. c) Both a and b. It is found that SBP has recently increased in prevalence with predominantly causative organism gram negative E Coli.