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IN THE MAY ISSUE of this journal Burrill and Greene1 reported that administration of relatively large doses of vitamin A to rats produces no effect on the normal estrous cycle nor does it modify the action of estrogens upon the vaginal epithelium of castrate rats. These findings stand in opposition to those of Sherwood and collaborators2 who found that feeding large amounts of carotene suppressed the normal estrous cycle. Last year we conducted experiments similar to those of Burrill and Greene but circumstances prevented their completion. However, they were carried to a point where we can state that wearrived at tentative conclusions similar to those of Burrill and Greene. In one set of rats(Sherman strain), after castration we maintained the animals in continuous estrus with minimal amounts of estradiol benzpate, injected subcutaneously. Then, simultaneous daily subcutaneous injection with vitamin A in sesame oil, 10,000 to 40,000 i.u. per day for 1 weeks, had no demonstrable effect upon the vaginal smear.