CLINICAL experience in the treatment of neurotic outpatients with tranquilizing drugs, as well as previous research,1-4has led us to expect that the role played by personality factors in response to treatment may be quite different in drug-treated and in placebo-treated patients. It is our belief that both similarities and differences, which emerge when the role of personality factors in the responses of drug- and placebo-treated patients are compared, may throw light upon the manner in which patient variables affect drug treatment, thereby having important methodological implications for psychopharmacological research. In this paper we shall consider the relationship of patient pretreatment anxiety level, derived from the Taylor Manifest Anxiety Scale (TMAS),5to patient report of side reactions and to a global rating of clinical improvement after a four-week course of treatment with either a minor tranquilizer or placebo. In general,