Background: Endoscopic retrograde cholangiopancreatography (ERCP) is a primary therapeutic modality for managing malignant and benign biliary obstruction. Technical success (TS) and clinical success (CS) of modality are essential indicators of procedural efficacy, which is influenced by various patient-and procedure-related factors. Therefore, this study aims to evaluate the TS and CS rates of ERCP and identify their predictors in patients with biliary obstruction at a tertiary referral center in Indonesia. Methods: A retrospective analysis was conducted on patients with biliary obstruction who underwent therapeutic ERCP at Cipto Mangunkusumo Hospital between January 2022 and December 2024. Patients with diagnostic ERCP or prehepatic/parenchymal jaundice were excluded. Results: A total of 259 patients were included (49.4% female, mean age 50.6 years) in this study. The results show that the TS rate is 96.5%, with multivariate analysis identifying ulcerative fragile papillary mass (AOR 0.075; P=0.001) as an independent negative predictor. Meanwhile, the CS rate is 88%, with pre-ERCP bilirubin >3 mg/dL (AOR 8.545; P<0.001) and previous ERCP stenting/pre-cutting (AOR 0.330; P=0.037) being independent predictors. Distal malignant obstruction causes a higher pre-ERCP bilirubin level (P=0.025) of >3 mg/dL (OR 6.116; P=0.011). Conclusion: ERCP showed high technical and clinical success rates in managing biliary obstructions. TS was negatively predicted by ulcerative fragile papillary mass. CS was positively predicted by pre-ERCP bilirubin >3 mg/dL and negatively by prior stenting or pre-cutting. These findings should be taken into consideration when planning and delivering ERCP to achieve better outcomes. © 2025, Indonesian Society of Internal Medicine. All rights reserved.