Background: Spontaneous Bacterial Peritonitis (SBP) defined as ascitic fluid infection without an evidence of intra-abdominal Source of infection. one of the most common and life-threatening complications of patients with cirrhotic ascites. It is a diagnostic and therapeutic emergency. Therefore it is important to determine the proportion and associated factors of SBP among cirrhotic patients with ascites attending Tibebe Gion specialized University hospital.. Methods and Materials: A hospital based retrospective study was conducted among 191 adult patients of decompensated liver cirrhosis with ascites in Tibebe Gion specialized University Hospital in the last 3years and 6months. The Data was collected using checklist from Patients’ Card by using systematic random sampling. Data were cleaned and checked for completeness, then entered into Epi Data 3.1, and exported to SPSS Version 23 for analysis. Descriptive statistics such as frequency, crosstab, and median were utilized. Binary logistic regression was conducted to identify candidate variables for multivariable logistic regression at a p-value of <0.05. Those variables whose P-value <0.05 in multiple binary logistic regression were considered as significantly associated variables with Spontaneous bacterial peritonitis. Result: A total of 191 patients were participating in the study. Of which 132 (69.1%) were males. Most of the patients were under the age of 50-years.The proportion of spontaneous bacterial peritonitis was 22.5% (95% CI: 16.2%–28.5%). The study also found that serum sodium<130meq/l[AOR = 15.599; 95%CI, 4.56, 53.33], upper Gastro-intestinal bleeding [AOR =16.951; 95% CI,4.50,63.87], INR>2.3 [AOR = 4.032; 95%CI, 1.13, 14.36], Hepatic Encephalopathy [AOR =3.07; 95% CI,1.01,9.31], Serum Albumin<2.5g/dl [AOR = 3.66; 95%CI, 1.30, 10.36] and Serum Bilirubin>3g/dl [OR = 2.552; 95%CI, 1.28, 5.10] were stasticaly significantly associated with spontaneous bacterial peritonitis.. Conclusions: SBP is common among patients with cirrhotic ascites admitted at TGSUH. Low serum sodium, low serum albumin, patients having upper gastro-intestinal bleeding, patients with hepatic encephalopathy, high INR and high bilirubin were highly associated SBP infection. Diagnostic paracentesis should be done immediately on admission to confirm the diagnosis and intervene early. Key Words: Ascites, Cirrhosis, SBP, Associated factors and TGSH