Abstract : A 31-year-old patient is admitted to the emergency room because of an acute right thoracic pain associated with a dyspnea. The patient reports the stopping of Decapeptyl®, a treatment taken in regards to an endometriosis, but interrupted to get pregnant. An x-ray highlights a pneumothorax of 15 mm at the right apical level. It is a second episode for this patient. Catamenial pneumothorax is one of the most frequent manifestation in terms of a thoracic endometriosis syndrome (TES). It concerns a rare pathology, unrecognized and underdiagnosed. The diagnosis should be invoked on all patients having the childbearing age who are presenting themselves at the emergencies with a right thoracic pain. The medical care is multidisciplinary, the association of a hormonal therapy and then a surgical treatment being the best therapeutical approach. This case report describes the recurrence of a catamenial pneumotorax induced by the stopping of the endometriosis treatment and reviews the physiopathology, the diagnosis and its multidisciplinary management.