Background: Spontaneous bacterial peritonitis (SBP) represent frequent and serious complications in cirrhosis patients with ascites. Our aim was to describe the clinical and bacteriological characteristics of SBP in Madagascar.Methods: This is a 21-month prospective study between January 2018 and October 2019, including hospitalized patients with cirrhosis, with clinical and biological symptoms of SBP.Results: Thirty-three patients were included. The mean age was 48.09 ± 13.55 years (extremes: 19 – 78 years), the sex ratio was 3.12. Abdominal pain (55%), fever (36%), diarrhea (6%), hepatic encephalopathy (18%) are the most common symptoms. Gastrointestinal bleeding (18.18%) was the main risk factor to SBP. SBP was community-acquired in 87.88% of cases. A culture of ascites fluid was positive for 9 patients (27.27%). The infectious agents found were Escherichia coli (12.10%), Klebsiella pneumoniae (3%), Pseudomonas (3%), Streptococcus mitis (9.1%). Escherichia coli were wild with one case resistant to Ceftriaxone. The Klebsiella were multidrug resistant. The other two pathogens did not show resistance. After antibiotic therapy adapted to the antibiogram, healing was observed in 26 patients (78.78%). Seven patients (21.22%) died from various complications. All deceased patients had bacteria identified in ascites fluid.Conclusion: SBP defined according to clinical and biological criteria is apparently sterile in the majority of cases. Gram-negative bacteria were the major pathogens involved in SBP in cirrhotic patients. Escherichia coli and streptococcus were the most common pathogen isolated. Bacteriological study is essential to adapt antimicrobial to multidrug-resistant bacteria.