This paper is a critical review of some of the experimental and clinical investigations, including some psychoanalytic studies, made to determine the effects of ovarian hormones on the psyche. The data obtained from experiments on the influence of hormones on human sexual behavior are very difficult to interpret. More significant, but still not conclusive, is the indirect evidence supplied by interpretation of the unconscious material of women undergoing psychoanalysis when correlated with bio-assays of hormone levels as reported by Benedek and Rubenstein. Freed and Kroger find the value of this evidence limited by the fact that the subjects were all neurotic and not normal women. They also suggest that the psychic behavior during the menstrual cycle may be due to an alteration in the anatomical and biochemical status of the various tissues coincidental with the presence of the sex hormones, rather than to the direct effect of any one of them.