The clinical signs and symptoms, the biological data and the prognosis of 38 cirrhotic patients with culture-positive spontaneous bacterial peritonitis and 15 cirrhotic patients with culture-negative neutrocytic ascites were compared. The diagnosis of culture-negative neutrocytic ascites was based on the following criteria: an ascitic fluid polymorphonuclear count greater than 250/mm3, a negative ascitic fluid culture and the absence of previous antibiotic therapy and intraabdominal source of infection. All patients were treated by antibiotic therapy. There were no differences in clinical signs and symptoms and Pugh grading between the two groups of patients. Serum creatinine and prevalence of positive-blood culture were higher in spontaneous bacterial peritonitis. Patients with culture-positive spontaneous bacterial peritonitis had a higher ascitic fluid polymorphonuclear count and a lower ascitic fluid pH. Mortality was higher in patients with culture-positive spontaneous bacterial peritonitis than in patients with culture-negative neutrocytic ascites (relative risk: 2.6, p less than 0.01): cumulative mortality was, respectively, 50% and 20% at 1 months, 61% and 33% at 6 months, 75% and 41% at 1 year. The higher mortality observed in patients with culture-positive spontaneous bacterial peritonitis persisted after hospitalization (relative risk: 3, p less than 0.03). Our results suggest that culture-negative neutrocytic ascites is a less severe variant of spontaneous bacterial peritonitis.