AFTER the publication of an article by Collins entitled, "Endometriosis of the Vermiform Appendix: Review of Literature, with Addition of Nine New Instances, One of Which Caused Severe Melena," which appeared in the A. M. A.Archives, 1 it now seems opportune to report five of my own cases. They had other types of clinical findings than those reported by Collins, though the endometrial tissue had the same unusual location. In 1932 to 1933, operations for endometriosis of the appendix were carried out in four cases, at the Maria Hospital, headed at that time by Prof. E. Key. In 1935 I made a short report to the Swedish Surgical Association of these and 31 other cases collected from the literature. Most of the latter are included in Collins' review, but reference to his footnotes shows that he failed to mention 11 cases. These 11 cases, my four, and another one