Background. Thoracic endometriosis is diagnosed as the presence of endometrial tissue in the thoracic cavity. Catamenial pneumothorax (CP) is most common clinical manifestation of thoracic endometriosis and is defined as a spontaneous recurrent pneumothorax that occurs in ovulatory women. CP generally occurs in women around 30 years old. The prevalence of CP in perimenopausal women may be considerably underestimated if these cases are treated as spontaneous pneumothorax. Catamenial or thoracic endometriosis-related pneumothorax occurring in perimenopausal women has not yet been reported to show laterality.Case presentation. We report two cases of CP in peri-menopausal women. In the first case, a 47-year-old G0P0 woman visited the hospital with recurrent pneumothorax that occurred three years after hysterectomy. In the second case, a 46-year-old G0P0 woman visited the hospital with four episodes of chronic recurring spontaneous pneumothorax in the past nine months.Conclusions. Disease awareness of pneumothorax in perimenopausal women may lead to improved treatment results, mainly reducing the recurrence rates of CP.