Since the experimental investigation of the effect of theelin (estrone) in involutional melancholia by Werner and his associates1in 1934, theelin has been administered to all patients received at Missouri State Hospital No. 4, Farmington, Mo., who had involutional melancholia, and to those whose mental condition was complicated by involutional psychoses. This procedure was not instituted with the hope that the substance would prove to be a panacea for all mental diseases but to alleviate the distressing subjective menopausal symptoms complicating other mental conditions. Frequently these symptoms obscure some other mental illness, making a diagnosis very difficult. In other words, we believe that we receive many patients suffering not only from some other definite psychosis but also from involutional melancholia. Involutional melancholia per se is considered generally as a distinct clinical entity, and the controlled research previously done with theelin by our group strengthens this contention. Of those patients