Background: Hemoptysis is a potentially serious clinical problem. However, there is no consensus on the clinical characteristics, treatment and patient outcome of catamenial hemoptysis. Objective: Clinical characteristics, treatments and outcome in patients of catamenial hemoptysis were evaluated. Methods: We conducted a retrospective nationwide observational analysis of Korean patients with catamenial hemoptysis. Results: Nineteen patients with catamenial hemoptysis were evaluated from 13 tertiary-care hospitals in Korea. The median age of the patients was 25 years; 8 (42%) were ever-smokers. Eight patients were pathologically diagnosed; 11 were diagnosed by clinical criteria. Sixteen (84%) patients had a history of obstetric or gynecological procedures before developing hemoptysis. The mean amount of hemoptysis (mean ± SD) was 58.3 ± 71.3 for surgery, 46.4 ± 33.2 for hormonal and 29.1 ± 26.3 for conservative treatment groups. Hemoptysis did not recur in 8 (89%) of 9 patients after surgery. None of the patients in the hormonal or conservative treatment groups had persistent hemoptysis. There was an excellent outcome (complete remission and partial responses) in all patients with conservative treatment, suggesting that endometrial cells implanted into the lung may have a benign course. Conclusion: Patients without massive hemoptysis can be treated conservatively or with hormonal agents.