IT HAS been shown that deficiency in vitamin A results in follicular hyperkeratosis. 1 Other lesions, including xeroderma, alopecia, ichthyosis and lichen planus, have been attributed to the same deficiency. 2 No reference was found to the possible part played by vitamin A deficiency in the development of keratosis seborrheica or keratosis senilis. In this study, 100,000 units of vitamin A were given daily for from fifteen to twenty-three months, with an average of nineteen and eight-tenths months, to a group of 50 patients. Three members of an original group of 53 were lost, 2 by parole and 1 by death. Except for 2 who were hospital employees, these were patients of Western State Hospital. This made possible an unusual degree of control of persons observed. Age grouping was as follows: ages'40 to 50, 8 persons; 51 to 60, 18 persons; 61 to 70, 11 persons; 71 to 80, 8