INTRODUCTION: A prospective study to determine the prevalence, clinical features and antibiotic susceptibility pattern of the micro-organisms isolated in cirrhotic patients with spontaneous bacterial peritonitis was undertaken over a nine-month period in Jos, central Nigeria. METHODS: The design was cross-sectional and descriptive. One hundred and twenty two consecutive patients (88 males and 34 females) with liver cirrhosis and ascites were recruited from the Medical Out-patients’ clinic, Emergency Department or Medical wards. Ascitic fluid (AF) white blood cell count was done using the conventional manual method and AF was inoculated directly into the blood culture bottles by the bed side. RESULTS: A total of 15 patients (12.3%) had SBP. Ten (8.2%) were culture positive, while 5 (4.1%) were culture negative neutrocytic ascites (CNNA). Five (4.1%) had monomicrobial nonneutrocytic bacterascites (MNB). All the patients with SBP and all those with sterile ascites had abdominal distension and ascites. The common clinical features in decreasing order were abdominal pain (73.3%), nausea (66.7%), positive peritoneal stretch tenderness (66.7%), icterus (60%), and vomiting (53.3%). Only 20% of the patients were febrile while one (6.7%) was hypothermic. Only 13.3% had the classical features of peritonitis- fever, abdominal pain and tenderness while up to 20% had none of these three features. 13.3% were asymptomatic. Escherichia coli was isolated in six cases, Staphylococcus aureus in two and Citrobacter spp and Klebsiella spp in a case each. Nine of the ten bacterial isolates were sensitive to ofloxacin, 7 to ciprofloxacin and 5 each to pefloxacin and ceftriaxone. None was sensitive to ceftazidime and coamoxiclav. CONCLUSION: The prevalence of SBP in Jos is comparable to those reported in other parts of Nigeria and Africa but lower than in most other parts of the world. The clinical features are very diverse and cannot be relied on for making a diagnosis. Gram negative bacteria especially Escherichia coli were the commonest organisms implicated and they were most sensitive to the fluoroquinolone ofloxacin.