Hereditary hemorrhagic telangiectasia (HHT, Osler-Weber-Rendu disease) is a rare autosomal dominant disease characterized by heterogenous multisystemic dysplasia of the vascular tissue. Prevalence of HHT is 1 in 5,000∼8,000. HHT commonly presents with recurrent epistaxis, but may have more serious consequences if visceral vascular beds are involved. Approximately 30∼50% of HHT cases also present with pulmonary arteriovenous malformation (PAVM). Spontaneous hemothorax is less common, and PAVM is one of the causes leading to hemothorax. Our case involved an 18-year-old female who had suddenly developed right chest pain. The reason for chest pain was due to right spontaneous hemothorax accompanied by PAVM in the right middle lobe. The patient was additionally diagnosed with HHT upon examination of her family history, specifically through her mother`s symptom that included recurrent epistaxis and mucosal telangiectasia.