The modern era in the treatment of psychotic disorders began in the early ’50s with the discovery of chlorpromazine. This was areal revolution and maybe the most important single contribution in the treatment of psychiatric illnesses. Clorpromazine and thesubsequent drugs that were introduced in the next 10–15 years, shared a common element in that they all were potent dopamine-2(D₂) receptor antagonists.The next landmark in the pharmacotherapy of psychoses was the introduction, in the early ’90s, of the novel or atypical or secondgeneration antipsychotics (SGAs). The prototype of these new drugs was clozapine, an “old” drug, originally synthesized in 1958. Whatall new agents have in common –in contrast to the traditional antipsychotics- is similar or greater activity at serotonin receptors than at dopamine type 2 receptors and for this reason they have been called serotonin-dopamine antagonists.