Pimozid (R 6238 Janssen, Beerse), a neuroleptic similar to the Butyrophenon type has a 24-hour period of effect due to the substance, and was used from 1969 onward on a total of 39 patients, predominantly from the range of schizophrenia types. The objective of thus clinical study was, above all, to plot the extent of its effects, define the optimal range of indications, to determine the most favourable dosage profile and to examine its tolerance in long-term use. Objectifying the medicinal effects, for example recording the psychopathological findings, proved successful with the aid of a syndrom catalogue following the AMP system, in comparison with preceeding and following treatments and considering the social-psychiatric aspects, so that concomitant- and side effects can be ascertained in the same way. The necessary maintenance dose of Pimozid, usually administered once a day, was set in relation to the daily dosage of Haloperidol, which had to be administered 2 to 3 times daily; the results, meanwhile, were compared with those already recorded on the literature. In agreement with this Pimozid proved to be a powerful and well tolerated neuroleptic, even in older patients, with a constant 24-hour effect which is suitable in doses from 1--10 mg/d particularly for long-term out-patient therapy, and above all for psychotics of the paranoid hallucinatory type.