Aneurysms arising from an intercostal artery are very rare vascular malformations in von Recklinghausen's neurofibromatosis, which often have a silent clinical presentation and are difficult to diagnose before rupture. We report a case of von Recklinghausen's neurofibromatosis with massive hemothroax caused by spontaneous rupture of an intercostal artery aneurysm in a 29-year-old man. The diagnosis was eventually confirmed by percutaneous angiography and treated with endovascular embolization. During a 10-month follow-up period, the patient had a satisfactory recovery. This case illustrates that angiography and possible endovascular embolization should be the first strategy in managing hemothorax in patients with von Recklinghausen's disease.