BACKGROUNDNo previous studies have compared respiratory clinics and respiratory specialized facilities regarding causative diseases for bloody sputum and hemoptysis in Japan.METHODSWe retrospectively compared causative diseases for bloody sputum and hemoptysis between 3 respiratory clinics (clinic group) and 7 departments of respiratory medicine at hospitals (hospital group) in Japan.RESULTSWe collected data from 231 patients (median age, 51 years; age range, 24-96 years; 109 men (47.2%)) in the clinic group and 556 patients (median age, 73 years; age range, 21-98 years; 302 men (54.3%)) in the hospital group. In the former group, the main causative disease was acute bronchitis (91 patients, 39.4%), acute upper respiratory tract infection (34 patients, 14.7%), and bronchiectasis (BE) (29 patients, 12.6%). In the latter group, the main causative diseases were BE (102 patients, 18.3%), lung cancer (97 patients, 17.4%), and non-tuberculous mycobacterial disease (NTM) (89 patients, 16%). In particular, in patients ≥60 years old, BE was an important causative disease for bloody sputum and hemoptysis in both groups.CONCLUSIONSThe present study is the first to compare respiratory clinics and respiratory specialized facilities. Depending on the facility in which the patient is examined, lung cancer, BE, and NTM were identified as diseases requiring special attention as causes of bloody sputum and hemoptysis.