THIS paper is devoted to the subject of persistent, aberrant mongolian spots, and a few comments will be made on differentiation of this condition from extensive blue nevus. Four cases are reported. REPORT OF CASES Case1.—Interest in the subject was first aroused through observation of a 23 year old Negro woman who presented a pigmented area on the left side of her face and nose, and bluish spots in her left eye, which spots had been present since birth. There was a palm-sized macular area of grayish green pigmentation on the left side of her face, extending from in front of the ear to the angle of the mouth, with a smaller spot on the side of the nose. In addition there were four discrete bluish macules on the left sclera. Histologic examination revealed a normal epidermis and dermis except for hemosiderin-free, dopa-positive melanoblasts situated in the middle third