The therapeutic as well as the physiologic implications of the biochemotherapies have been stressed; the development of 4 of them, thyroid and sex steroids, insulin and histamine, has been sketched; some of our physiologic and clinical data and observations have been integrated into a brief review of a formulation linking fundamental biochemical processes to the etiology and pathogenesis of certain psychiatric disorders. This concept has been presented as historically consistent with the deductions of Kraepelin, Freud, Bleuler, and Jelgersma as to the participation of endogenous biochemical factors in schizophrenic causation.In conclusion, it is submitted that some of the most severe of the psychiatric disorders are no more a primary disease of the brain by itself than the exophthalmous of hyperthyroidism is a primary ocular disease or that diabetes is a primary disease of the blood or kidneys. It is proposed that the outlook even in the most malignant psychiatric processes is being dramatically improved by the early administration of such relatively simple and effective therapeutic agents as histamine and the sex steroids. The ultimate definition of the biochemical processes associated with mental disease must lead to an advanced science of psychiatry in which preventive therapy—biochemical as well as psychologic—will come into its own.Abstract Teaser