This study is sought to evaluate the feasibility and safety of using ¹²⁵I seed strands for intraluminal brachytherapy (ILBT) in the treatment of malignant obstructive jaundice (MOJ), and its clinical effect on stent patency. A total of 34 patients found to have MOJ were randomly assigned to an ILBT treatment group or a control group before biliary stent insertion. For the ILBT group, ¹²⁵I seed strands were implanted into the obstructive segment of the bile duct after stent insertion. For the control group, only the biliary stent was inserted. Alimentary and hematologic complications were examined for patients in the ILBT group. The stent patency of the two groups were compared. In the ILBT group, the number of ¹²⁵I seeds per strand varied from 6 to 16 (mean, 10.9), and were successfully implanted in 17 patients. Serum levels of bilirubin, alanine aminotransferase, granulocytes, and platelets assayed 2 and 4 weeks following the procedure demonstrated no significant difference between the ILBT group and the control group. The mean stent patency for ILBT group (10.2 months) was significantly longer than that of the control group (7.2 months, p=0.032). ¹²⁵I seed strands for ILBT is a feasible and safe palliative therapy for the treatment of MOJ, and may prolong stent patency.