The prognosis of patients with biliary tract cancer remains unsatisfactory even with surgery owing to the high recurrence rate. Therefore, an effective adjuvant chemotherapy is required to prolong survival. A few randomized controlled trials in patients with limited biliary tract cancer have been reported, but the efficacy of adjuvant chemotherapy could not be clarified. To date, effective adjuvant chemotherapy with evidence has not been established, and the standard therapy for patients with resectable biliary tract cancer has only been surgical treatment. Recently, a number of newer toxic agents have been shown to induce response in patients with advanced biliary tract cancer. Moreover, the morbi-mortality rate of operation for this cancer has been decreasing owing to advances in operative techniques and perioperative management. Given this background, a number of adjuvant chemotherapy trials have been started using gemcitabine, capecitabine, S-1, and combination chemotherapy with platinum. The results of these trials will be reported in the near future. Overall, the important aspects of adjuvant chemotherapy for biliary tract cancer are to establish well-organized and active clinical trial study groups, to conduct well-designed multicenter randomized controlled trials, and to continue such trials without interruption in the future.