A BSTRACT Introduction and Objective: Hilar cholangiocarcinoma (HCCA) is a rare malignancy in patients with biliary disease. If jaundice and obstruction before surgery are left untreated, then they can cause side effects such as cholangitis, delayed tumor treatment, decreased quality of life, and increased mortality. Surgery is the main treatment for HCCA. Therefore, this study was performed to compare the efficacy and complications of percutaneous transhepatic biliary drainage (PTBD) and endoscopic biliary drainage (EBD). Methods: This cohort study was conducted on 20 patients with biliary obstruction who had been selected by simple random sampling and divided into two groups of EBD and PTBD. Three weeks after surgery, patients were compared in terms of bilirubin levels and postoperative complications. Data were analyzed by descriptive statistics (table, mean, and standard deviation) and inferential statistics (independent t-test, Chi-square test, and Fisher’s test). Results: Independent t -test did not show a significant difference between the two groups in terms of bilirubin level ( P = 0.77). However, despite a decrease in bilirubin level in both groups, independent t-test showed that this difference was not significant ( P = 0.08). Fisher’s exact test showed a significant difference between the two groups in terms of postoperative complications ( P = 0.02). Conclusion: Using both drainage methods before surgery reduced bilirubin levels in patients, but EBD method had fewer side effects than PTBD method. The EBD method was performed under the direct supervision of a gastroenterologist. In performing this procedure, specialist physicians should have more supervision.