Menstruation-related spontaneous pneumothorax (MSP), also termed catamenial pneumothorax, is a syndrome of spontaneous pneumothorax during menstruation due to endometriotic lesions in the diaphragm and thoracic cavity. Previously MSP was considered rare, and to cause only 3-6% of all spontaneous pneumothoraces in otherwise healthy women. Current data suggest that the incidence is substantially higher and MSP might be the reason for spontaneous pneumothoraces in up to 25-33% of all cases in women of reproductive age. The typical characteristics are a high recurrence rate and diaphragmatic spread of endometriotic lesions. We report six patients who had been diagnosed to have diaphragmatic endometriosis and four of them had developed MSP. Optimal management requires flexible collaboration between thoracic surgeons and gynecologists. Although treatment is primarily surgical, long-lasting and successful management requires that amenorrhea is induced with hormonal therapy, either by continuous contraceptives, progestins, the levonorgestrel-releasing intrauterine device or GnRH-agonists.