Introduction: In Japan, balloon pulmonary angioplasty (BPA) is more commonly adopted in patients with chronic thromboembolic pulmonary hypertension (CTEPH) compared to European countries or US due to their expertise. However, there are no reports from regions where BPA is extensively practiced. Aims: This study aims to explore the treatment outcomes in Japan. Methods: The study involved a nationwide, prospective, observational registry that included all patients diagnosed with CTEPH from August 2018 to February 2023 in Japan. Patients were categorized as naïve or prevalent cases based on their previous reperfusion therapy (pulmonary endarterectomy and/or BPA) at the time of enrollment. Each case was further classified as operable or BPA group. The primary outcome measure was morbidity and mortality (MM) events since enrollment, which comprised all-cause death, CTEPH-related hospitalization, rescue reperfusion therapy, initiation of parenteral pulmonary vasodilators, and worsening of CTEPH characterized by a decrease in 6-minute walk distance greater than 15% and deterioration of the WHO functional class. Results: A total of 1194 patients, including naïve cases (operable: n = 54, BPA: n = 293) and prevalent cases (operable: n=125, BPA: n = 532), were identified. Among the naïve cases, there were no significant differences in age or disease severity between the operable and BPA groups. Among the prevalent cases, the BPA group was older (63 ± 13 vs. 58 ± 14 years old, p < 0.0001) and had higher pulmonary vascular resistance (364 ± 279 vs. 293 ± 206 dyne*sec/cm5, p = 0.001) compared to the operable group. The results of primary outcome measures were comparable between both the groups (Figure). Conclusions: BPA as well as pulmonary endarterectomy is considered as safety and effective therapeutic option in CTEPH patients.