Biliary fistula, a complication of hepatobiliary surgery, requires attention. Although the usefulness of endoscopic treatment has been reported in recent years, no standard treatment has yet been established. We report two cases of postoperative biliary fistulas treated endoscopically at our hospital in 2021. The patients were aged 78 and 82 years and were both men. Both of them underwent endoscopic retrograde biliary drainage (ERBD) and open drainage, together with closure of their biliary fistulas. There were no short-term and long-term complications. Endoscopic treatment of postoperative biliary fistulas usually takes the form of endoscopic nasobiliary drainage, but this can cause distress and is associated with a risk of accidental removal, especially in older patients. In contrast, ERBD can also provide effective drainage and has no such attendant risks.