['Acute ascending cholangitis usually is treated with antibiotics, and biliary drainage is treated by endoscopic retrograde cholangiopancreatography (ERCP). We investigated the effects of the timing of ERCP on outcomes of patients with acute cholangitis factors that predict prolonged hospital stays, increased costs of hospitalization, and composite clinical outcomes (death, persistent organ failure, and admission to the intensive care unit).', 'We performed a retrospective analysis of data from 90 patients (mean age, 60 y; 48% female) admitted to Johns Hopkins Hospital from January 1994 to June 2010 who were diagnosed with acute cholangitis and underwent ERCP. A delayed ERCP was defined as one performed more than 72 hours after admission. Electronic and paper medical records were reviewed, and relevant data were abstracted.', 'ERCP was performed successfully in 92% of the patients, at a mean time period of 38 hours after admission (14% of ERCPs were delayed). Factors that were associated independently with prolonged length of hospital stay (top 10%) included unsuccessful ERCP (odds ratio [OR], 52.5; P = .002) and delayed ERCP (OR, 19.8; P = .008). Factors associated with increased hospitalization cost (top 10%) included unsuccessful ERCP (OR, 33.8; P = .004) and delayed ERCP (OR, 11.3; P = .03). Factors associated with composite clinical outcome included age (OR, 1.1; P = .01), total level of bilirubin (OR, 1.36; P = .002), and delayed ERCP (OR, 7.8; P = .04).'] Are delayed and unsuccessful endoscopic retrograde cholangiopancreatography associated with worse outcomes in patients with acute cholangitis?