Objective To investigate the clinical efficacy of percutaneous transhepatic insertion of biliary stent (PTIBS) combined with radioactive seed implantation in treating malignant biliary obstruction. Methods A total of 38 patients with malignant biliary obstruction were enrolled in this study. Radioactive 125I seed was used, and each 125I seed was 4.5 mm in length and 0.8 mm in diameter. The 125I seeds were placed in a catheter to prepare the 125I seed- strip. PTCD was carried out first, then percutaneous catheterization was performed and a guide- wire was inserted through the catheter until it passed the obstructed biliary segment. The obstructed segment was dilated by a balloon - catheter, which was followed by PTIBS. An 8 - 10 F drainage - catheter was placed into the biliary duct through the stent. Finally, guided by fluoroscopy the catheter with the 125I seed- strip was inserted via the drainage- catheter to the area that was planned to be radiated. The external drainage- catheter was wrapped and fixed to the skin, or was imbedded under the skin. Results Of the 38 patients with malignant biliary obstruction, successful PTIBS combined with radioactive seed implantation was accomplished in 36 patients. After the treatment, the serum bilirubin level fell to normal or near normal range in all patients (P < 0.05). No obvious side effects were observed. Conclusion For the treatment of malignant biliary obstruction, percutaneous transhepatic insertion of biliary stent combined with radioactive 125I seed - strip implantation is a safe and effective method.