Parenchymal pulmonary endometriosis is the likely cause in patients with hemoptysis, dyspnea, or chest pain during menstruation. Embolization of endometrial tissue from the uterus to the lungs via the pulmonary arteries has been proposed for the mechanism of the development of parenchymal pulmonary endometriosis. This is a report of a woman with catamenial hemoptysis which was responded successfully to danazol therapy; however, hemoptysis resumed after cessation of therapy. The patient was subsequently treated with danazol again because she refused surgical treatments.