Early in our clinical studies with the phrenotropic drugs, reserpine and chlorpromazine, we observed that psychotic patients receiving them were more resistant to treat for infectious processes that occurred during their hospitalization (Saunders, 1961). We also observed that in experimental animals, the LD50 of a standardized dose of bacteria was significantly increased if the rats had been previously treated with a phenothiazine. Preliminary observations led us to consider the role of these drugs in protein synthesis, with specific interest in the gamma globulin, since antibodies are associated almost exclusively with this fraction. Further interest in the problem of protein synthesis was stimulated by the reduced albumin and increased globulin levels found in most chronic psychoses, as the phrenotropic drugs are capable of significantly shifting this ratio toward normal. The question of phrenotropic drug action on antibody synthesis was asked at the Second International Congress of Psychiatry in September, 1957, and no specific information was known to the participants (Saunders, 1958). With this background, the question warranted further study in man. We designed our experiment to measure antibody response to oral poliovirus vaccine, Cox strains types 1 and 3, during phenothiazine therapy.