The aim of this study was to analyze the patency of expandable metallic stents in malignant biliary obstruction and to evaluate the efficacy of adjuvant therapy accompanied by biliary stenting. We analyzed 29 patients in whom bile duct stenting was performed for malignant biliary obstruction. Their types of disease were: hilar ductal carcinoma (n = 8), gallbladder carcinoma (n = 11), and pancreatic carcinoma (n = 10). Initially, 46 expandable metallic stents were placed in 29 patients. In 23 of the 29 patients, adjuvant therapy was administered. Seventeen patients underwent radiotherapy, and 16 patients received various systemic chemotherapies. In principle, hyperthermia was performed twice a week, simultaneously with radiotherapy. Patient survival and the probability of stent patency were calculated using actuarial life table analysis. There was no significant difference in stent patency among the patients according to type of disease. Hyperthermia did not influence the stent patency rate. The median stent patency time was significantly greater in the chemo-radiation group than in the no-adjuvant therapy group: 182 days versus 68 days, respectively (P = 0.017). Moreover, a significant increase was seen in the median survival time in the chemo-radiation group: 261 days versus 109 days (P = 0.0337). Complications occurred in 9 patients (31.0%). Stent occlusion occurred in 6 patients (20.7%), with all of these patients managed successfully using a transhepatically placed new expandable metallic stent, employing the stent-in-stent method. Stent migration occurred in 2 patients after radiotherapy. Adjuvant therapies such as radiotherapy and systemic chemotherapy, in combination with stent insertion, resulted in an increase in the patency period of expandable metallic stents and in increased patient survival time.