Severe late effects occurred after the treatment of esophageal cancer by external irradiation and simultaneous intraluminal hyperthermo-brachytherapy. This is the first case report on late side effects. A 73-year-old man was treated with radiotherapy alone according to his decision. The stage was T2N0M0 according to the 1987 UICC. External irradiation of 40 Gy/20 fr was delivered followed by simultaneous intraluminal hyperthermo-brachytherapy once weekly for four weeks (16 Gy/4 fr). Complete response was achieved. Eight months later, local recurrence and ulcer were found, and surgery was performed. The specimen showed healing of an ulcer acknowledged before surgery and another deep ulcer next to the tumor that penetrated the adventitia, which was close to perforation. The histopathologic specimen showed severe stenosis of muscular arteries in the adventitia, which was caused by fibrosis of the endothelium. The findings suggested that enhancement might be occurred with this combined therapy.