In order to identify the predictive factors of hospital mortality in cirrhotics with spontaneous bacterial peritonitis (SBP), we studied 64 patients who fulfilled the accepted diagnostic criteria. All cases were treated with cefotaxime up to 2 days after the infection was considered cured (7.7 +/- 2.9 days). Eleven patients (17%) died while in hospital, six of them before SBP was cured. After uni- and multivariate analyses, only seven routine clinical, biological, and bacteriological variables studied were independently associated with hospital mortality. These were: the presence of upper gastrointestinal bleeding at admission (beta = 2.01), the absence of abdominal pain as presenting symptom (beta = -1.29), the polymorphonuclear count (%) in the ascites (beta = 0.48), prothrombin rate (beta = -0.22), and serum Na (beta = -0.64), creatinine (beta = 0.50), and cholesterol (beta = -0.68). When the equation obtained was computed in a randomly selected sample of the patients studied, it correctly predicted the outcome in 92.3% of the cases. We conclude that short-term outcome of SBP patients depends on the existence of recent gastrointestinal bleeding, the severity of SBP, and the degree of liver and renal failure. The prognostic value of this model needs prospective validation in a new series of patients.