Thoracic endometriosis syndrome is an uncommon entity with varied clinical manifestations. Its pathogenesis is not understood completely. Recurrent unilateral right-sided pneumothorax that occurs within days of the onset of menstruation is the most common presentation. Clinical suspicion and recognition of the temporal relationship of the patient's symptoms with menses are essential to establish the diagnosis. Radiographic studies, bronchoscopy, and thoracoscopy may support the diagnosis. Pathologic evidence of thoracic endometrial tissue is not present universally. Therapeutic interventions, which include medical and surgical options, must be individualized for each patient.