Spontaneous hemothorax is a rare but life-threatening condition. Vascular manifestations of neurofibromatosis type 1 (NF1), or Von Recklinghausen disease, are rare, but may be fatal if they are disrupted. We report the case of a 37-year-old woman with NF1 who developed a spontaneous right massive hemothorax caused by a branch of the right subclavian artery. We successfully performed direct surgical ligation of the bleeding vessel, and the patient's recovery was uneventful. Spontaneous hemothorax in patients with NF1 is a life-threatening condition and may require emergency surgery or endovascular embolization/stenting, depending on the hemodynamic status.