To evaluate associations among catamenial pneumothorax, pelvic endometriosis, and fertility status. Retrospective study (Canadian Task Force classification II-2). Departments of Thoracic Surgery and Obstetrics and Gynecology, San Raffaele Hospital, Milan, Italy. Sixteen females referred to the Department of Thoracic Surgery for treatment of spontaneous pneumothorax between January 2001 and January 2014 and referred to the outpatient clinic for gynecologic follow-up. Thoracoscopy for catamenial pneumothorax and laparoscopy for pelvic endometriosis. Characteristics of the patients, the presence of endometriosis, and their fertility status were statistically analyzed. Pelvic endometriosis was diagnosed in 9 patients (56.3%), but 6 patients did not undergo a laparoscopic procedure to confirm or exclude the disease. Seven of the affected patients (77.8%) had stage III-IV endometriosis. Two-thirds of the patients with pelvic endometriosis who attempted conception conceived spontaneously, as did all of the patients without histopathological confirmation of endometriosis. Thoracic endometriosis syndrome, characterized mainly by catamenial pneumothorax, is a relevant condition in patients affected by endometriosis. However, few previous studies have analyzed this condition from a gynecologic standpoint, in terms of characteristics of endometriosis and fertility status of affected women. Our findings support the presence of a strong association between catamenial pneumothorax and pelvic endometriosis, as well as a minimal effect of catamenial pneumothorax on fertility status, even in the presence of pelvic endometriosis.