Endovascular aneurysm repair (EVAR) has been widely accepted as a safe and effective treatment for abdominal aortic aneurysm. Endoleaks are the most common complication after EVAR and require urgent interventions. Usually endoleaks can be treated with endovascular procedures using a variety of techniques. Despite these interventions, if the endoleak still persists, conventional open surgery should be evaluated. A 67-year-old man had been treated with EVAR after a ruptured abdominal aortic aneurysm 7 years ago. Later on, a type II endoleak was detected due to the inferior mesenteric artery and treated with coil embolization at the first follow-up year. The patient was admitted to our emergency department due to abdominal pain. Computed tomography angiography demonstrated a type Ia endoleak from the posterior side of the graft with a huge abdominal aortic aneurysm sac (22.9 cm) without rupture. The patient was hemodynamically unstable, and open surgical repair was performed via left anterolateral thoracotomy and laparotomy. Here we report a case where we performed open repair of a type Ia endoleak and discuss the repairing techniques for type Ia endoleak in the light of the literature.