PURPOSE: To evaluate the efficacy of combined treatment of metallic biliary stent placement and radiotherapy in malignant biliary obstruction. MATERIALS AND METHODS: Between January 1992 and February 1994, 22 patients with malignant biliary obstruction were treated with metallic biliary stent placement and radiotherapy. The causes of the obstruction included cholangiocarcinoma(n=14), gallbladder carcinoma(n=4), colon cancer(n=2), pancreatic head cancer (n=1), and stomach cancer(n=1). According to the sites of obstruction level, patient were divided into 2 groups; hilar obstruction(n=18) and common bile duct obstruction(n=4). The patients received dose of 45 Gray/18 fraction by external radiotherapy and 20Gy/8f by high dose rate brachytherapy with iridium--192 source through percutaneous transhepatic biliary drainage(PTBD) catheter. The duration of stent patency after placement, survival period and survival rate by Kaplan Meier method were calculated in dead and alive patients, respectively. RESULTS: In all 22 patients, the duration of stent patency was 5.5(1.3--18.5)months. Survival periods after stent placement and PTBD were 5.3(2.0--8.5 )months and 7.9(4.0--14.7)months respectively in 9 dead patients and 7.7(1.3--21.0)months and 9.5(2.3--23.0)months in 13 alive patients. In all 22 patients, the survival rates in 6, 12 and 18 months were 78.9%, 47.5 % and 35.6 %, respectively. CONCLUSIONS: The results with combined metallic biliary stent placement and radiotherapy for the palliative treatment of malignant biliary obstruction in this study was more favorable, as compared with those of the other authors with only metallic biliary stent placement.