The Child-Pugh classification is a simple, convenient prognostic measure in patients with liver cirrhosis. We investigated the relative role of the Child-Pugh classification and the Mayo model in the assessment of survival in patients with primary sclerosing cholangitis (PSC). Of the 173 patients described in the original Mayo PSC natural history model, 147 patients had sufficient information in the medical record to allow computation of the Child-Pugh score. We used our most recent modification of the Mayo model to compute the risk score, based on patient's age, serum levels of bilirubin, albumin, and aspartate aminotransferase and history of variceal bleeding. Using the risk score (R), patients were divided into the low- (R < 0), intermediate- (0 </= R < 2), and high-risk (R >/= 2) groups. Kaplan-Meier estimates and proportional hazards analysis were used to evaluate the two prognostic models. Although there was a statistically significant correlation between the Child-Pugh and Mayo risk scores, two-thirds of the patients had a Child-Pugh score of 5 or 6 and a relatively wide range of risk scores (-1.1-4.3). The probability of survival for 7 years in patients in the low-, intermediate-, and high-risk groups was 92%, 74%, and 40% for Child-Pugh class A (n = 96) and 100%, 62%, and 28% for Child-Pugh class B patients (n = 44), respectively. There were only a small number (n = 7) of Child-Pugh class C patients. In our age-adjusted multivariate analysis, each unit increase in the Mayo risk score was associated with a 2.5-fold increase in the risk of death (95% confidence interval: 1.8-3.4, P <.01), whereas Child-Pugh classification had no significant impact on survival (Child-Pugh B vs. A: risk ratio = 1.1 [95% confidence interval: 0.6-2.0]; Child-Pugh C versus A: risk ratio = 0.6 [95% confidence interval: 0. 2-1.8]). In contrast to the Child-Pugh classification, which was developed for advanced liver cirrhosis, the Mayo model provides valid survival information, particularly in patients early in the course of PSC.