An epidemiologic study was done on spontaneous pneumothorax in women. Six hundred sixty-four patients with spontaneous pneumothorax comprising 409 with idiopathic pneumothorax (61.6 percent), and 255 with secondary pneumothorax (38.4 percent) were studied. By age, idiopathic pneumothorax had its peak incidence in the 20s and secondary pneumothorax the 30s. Secondary pneumothorax included iatrogenic pneumothorax resulting from acupuncture treatment. The female patients were not so thin and tall as the male patients. The percentage of positive family history among the female patients was 4.42 percent in the idiopathic type and 0.45 percent in the secondary type. The percentage in the male idiopathic type of pneumothorax was 2.29 percent. Catamenial pneumothorax and pneumothorax with pulmonary hamartoangiomyomatosis are well known as specific in female subjects, but the cases are rare. Nonetheless, attention should be paid to female-specific rare types, for the etiology of idiopathic pneumothorax.