BACKGROUND Spontaneous bacterial peritonitis (SBP) is a common bacterial infection in patients with cirrhosis and ascites requiring prompt recognition and treatment. The aim of this study was to determine the prevalence, and characteristics of SBP among in-patients with cirrhosis and ascites seen at our facility. METHODS Thirty one patients with liver cirrhosis and ascites who were admitted into the Medical ward of the Ekiti State University Teaching Hospital (EKSUTH), Ado-Ekiti, Nigeria from August 2009 to July 2010 were retrospectively studied. All the patients had abdominal paracentesis done within 48 hours of admission under aseptic condition and the data obtained were analyzed. RESULTS The mean age of the studied population was 62±9 years (age range 43-78 years). Of the 21 that developed SPB, culture positive SBP was present in 66.7% (14/21) while CNNA was found in 33.3% (7/21). The prevalence of MNB was 26% (8/31) in this study. Of those with SBP, 93% had monomicrobial infection with aerobic Gram negative bacilli being responsible in 66.7% of the cases with E. coli (70%) being the predominant organism followed by Klebsiella species. Gram positive organisms accounted for 33.3% with Streptococcal species (60%) being the predominant organism followed by Staphylococcus aureus (40%). Patients with SBP had significantly lower platelet count when compared with those without SBP, p < 0.05. Also, international normalization ratio (INR) was significantly higher in those patients with SBP compared with those without SBP, p < 0.05. The poor prognostic indicators found in this study were; low ascitic protein, hepatic encephalopathy, coagulopathy, renal dysfunction (creatinine >2 mg/dl) and leukocytosis (p < 0.05). CONCLUSIONS It is therefore imperative to do diagnostic abdominal paracentesis for cell count and culture in any patient with onset of ascites or cirrhotic patients with ascites and suggestive symptoms compatible or suggestive of SBP.