©2018 by The American College of Gastroenterology. BACKGROUND:Data on the outcome of adverse events (AEs) and the risk of developing acute-on-chronic liver failure (ACLF) after ERCP in patients with cirrhosis are unknown. We examined the incidence and risk factors of post-ERCP AEs in patients with cirrhosis and the appearance of ACLF after ERCP.METHODS:In this multicenter, retrospective, matched-cohort study, we evaluated ERCPs performed from January 2002 to 2015. A group of patients with cirrhosis with non-ERCP interventions and one without interventions was also analyzed for the development of ACLF.RESULTS:A total of 441 ERCPs were analyzed; 158 in patients with cirrhosis (cases) and 283 in patients without cirrhosis (controls). The overall rate of AEs after all ERCPs was significantly higher in cases compared to controls (17% vs 9.5, p = 0.02). Cholangitis developed more in cases compared to controls (6.3% vs 1.8%; p = 0.01). In a subanalysis of those with sphincterotomy, the rate of bleeding was higher in those with cirrhosis (9.4% vs 3.4%; p = 0.03). Logistic regression identified cirrhosis (OR, 2.48; 95% CI, 1.36-4.53; p = 0.003) and sphincterotomy (OR, 2.66; 95% CI, 1.23-5.72; p = 0.01) as risk factors of AEs. A total of 18/158 (11.4%) cases developed ACLF after ERCP. ACLF occurred in 7/27 cases with post-ERCP AEs and in 11/131 without post-ERCP AEs (25.9% vs 8.3%; p = 0.01). A total of 3.2% (13/406) patients without interventions developed ACLF compared to 17.5% (102/580) who developed ACLF after non-ERCP interventions. Patients with decompensated cirrhosis at ERCP had a higher risk of developing ACLF (17% vs 6.8%; p = 0.04). Patients with a MELD score ≥ 15 were 3.1 times more likely (95% CI: 1.14-8.6; p = 0.027) to develop ACLF after ERCP.CONCLUSIONS:The rate of AEs after ERCP is higher in patients with cirrhosis compared to the non-cirrhotic population. The incidence of ACLF is higher in those with AEs after ERCP compared to those without AEs, especially cholangitis. The development of ACLF is common after ERCP and other invasive procedures. ACLF can be precipitated by numerous factors which include preceding events before the procedure, including manipulation of the bile duct, and AEs after an ERCP.