The rôle played by roentgen therapy in the occurrence of scars following the treatment of acne vulgaris by this agent has long been a disputed question. Every physician who has had experience in treating this disease with roentgen rays has repeatedly been forced to reassure many patients on this point because they have heard numerous, dire tales from friends about the unsightly scars thus produced. For a long time, it had been my opinion that this belief was limited to those outside the medical profession, but recently Dr. George Miller MacKee told me that it was also held by many physicians and a few outstanding dermatologists. At his suggestion. I have attempted to settle this question in the following manner: In forty consecutive, unselected cases of acne vulgaris, seen in the dermatologic department of the New York Post-Graduate Hospital from Oct. 16, 1930, to June 1, 1931, one-fourth