BACKGROUND In the intensive care unit (ICU), critically ill patients with cirrhosis and acute-on-chronic liver failure (ACLF) continue to have high mortality rates. The AARC ACLF score is a simple, newly-developed score based on Asian ACLF patients, which performs well in prognosis. The present study attempted to verify the prognostic ability of AARC ACLF in non-Asian critically ill patients with cirrhosis and ACLF. MATERIAL AND METHODS We enrolled 786 patients. Relevant clinical data were collected within 24 h after admission to compare the differences between survivors and non-survivors, and all the patients were followed up for at least 180 days. RESULTS The 28-day, 90-day, and 180-day mortality rates were 28.9% (227/786), 36.4% (286/786), and 40.3% (317/786), respectively. Multivariate Cox regression analysis showed that AARC ACLF score (HR: 1.375, 95% CI: 1.247-1.516, P