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