Imipramine hydrochloride (Tofranil) has found its chief clinical application in the treatment of depressive states. Clinically, it acts neither as a sedative nor like a tranquillizer. Furthermore, its effects are very different from the amphetamine group of stimulants and psychoenergizers, i.e., in contrast to these, it does not inhibit monoamine oxidase. The purpose of the present study, however, was not to investigate the therapeutic effects of imipramine hydrochloride but rather to study the responsiveness of the experimental subjects to the drug. It has been reported that imipramine hydrochloride activates the psychotic process in schizophrenic patients1,6,7,9without producing any major change in the mental status of normals and neurotics.3It seemed that imipramine hydrochloride could be used as a tool to manipulate the psychotic process and perhaps to reveal differences between diagnostic subgroups in order to contribute to further understanding of psychotic processes.