Cirrhotic patients admitted to the medical intensive care unit (ICU) are associated with high mortality rates. The prognosis of critically ill cirrhotic patients is determined by the extent of hepatic and extrahepatic organ dysfunction. This study was conducted to assess and compare the accuracy of the Child-Pugh classification and APACHE II scores, obtained on the first day of ICU admission, in predicting hospital mortality in critically ill cirrhotic patients. One hundred thirty-five patients diagnosed with liver cirrhosis were admitted to the medical ICU between January 2002 and March 2003. Information considered necessary to compute the Child-Pugh and APACHE II scores on the first day of ICU admission was prospectively collected. The overall hospital mortality rate was 66.6%. Liver disease was most commonly attributed to hepatitis B viral infection. The APACHE II scores demonstrate a good fit using the Hosmer and Lemeshow goodness-of-fit test. Furthermore, by using the areas under receiver operating characteristic (AUROC) curve, the APACHE II scores demonstrated a better discriminative power (AUROC 0.833 +/- 0.039) than Child-Pugh scores (AUROC 0.75 +/- 0.05) (P=.024). This investigation confirms the grave prognosis for the cirrhotic patients admitted to the ICU. While both Child-Pugh and the APACHE II scores can satisfactorily predict the outcomes for critically ill cirrhotic patients, APACHE II is more powerful in discriminating the survivors from the nonsurvivors.