Budd-Chiari syndrome (BCS) is a rare disorder that is characterized by hepatic venous outflow obstruction. The aim of this study was to assess determinants of survival and to evaluate the effect of portosystemic shunting. In this international multicenter study, 237 patients with BCS, diagnosed between 1984 and 2001, were investigated. Univariate, multivariate, and time-dependent Cox regression analyses were performed. Overall survival at 1, 5, and 10 years was 82% (95% CI, 77%-87%), 69% (95% CI, 62%-76%), and 62% (95% CI, 54%-70%), respectively. Encephalopathy, ascites, prothrombin time, and bilirubin were independent determinants of survival. A prognostic classification combining these factors could identify three classes of patients (classes I-III). The 5-year survival rate was 89% (95% CI, 79%-99%) for class I, 74% (95% CI, 65%-83%) for class II, and 42% (95% CI, 28%-56%) for class III. Anticoagulants were administered to 72%; only for patients in class I was this associated with a trend toward improved survival (relative risk [RR], 0.14; 95% CI, 0.02-1.21). Portosystemic shunting was performed in 49% of the patients (n = 117); only for patients in class II, time-dependent analyses suggested an improved survival (RR, 0.63; 95% CI, 0.26-1.49). In conclusion, at the time of diagnosis, patients with BCS can be classified into good (I), intermediate (II), and poor (III) prognostic classes, according to simple baseline clinical and laboratory parameters. Our results suggest an improved survival after surgical portosystemic shunting for patients with an intermediate prognosis (class II).