A review of the medical records of patients diagnosed as having “spontaneous bacterial peritonitis” (SBP) revealed 18 episodes of culture-negative neutrocytic ascites (CNNA) in 17 patients. The following criteria were all required in order to qualify for this diagnosis: (i) an ascitic fluid neutrophil count greater than 500 cells per mm3; (ii) negative ascitic fluid culture (5); (iii) absence of an intraabdominal source of infection; (iv) no antibiotic treatment within 30 days, and (v) no evidence of pancreatitis. Five patients had positive blood cultures. Two patients with CNNA had SBP in the past, and two other patients, who survived the episode of CNNA, subsequently developed SBP. Clinical signs and symptoms of patients with CNNA were not different from those of 32 patients with 33 episodes of culture-positive SBP. The mortality of CNNA (50%) was not different from that of SBP (70%). Because of the high mortality and because of the similarity of CNNA to SBP, it is presumed that many patients with CNNA have bacterial infection of their ascitic fluid, and it is recommended that they be treated with antibiotics.