In his attempts to estimate the comparative value and potency of a neuroleptic agent the clinician may frequently find his primary impressions corrected or modified through prolonged and extensive use of the drug in question,The "fate" of the butyrophenone derivative floropipamide (DipiperonB) in this hospital may serve as an illustration. As a result of a pilot study conducted in 1963 on 70 schizophrenic women we were inclined to classify this drug as a potent anti-psychotic agent, similar in action to the piperazinated phenothiazines. At a later period a controlled comparative trial on 16 schizophrenic patients of both sexes failed to demonstrate any difference in action and side effects between floropipamide and chlorpromazine. To-day being more familiar with the drug we feel justified in our estimation of floropipamide as belonging to the predominantly sedative neuroleptics, with an anti-psychotic potency and side-effects placing it at a level between chlorpromazine and chlorprothixene.As on the other hand the first representative of the butyrophenone-series, haloperidol (SerenaseB) seems to maintain its position as a potent, low dosage neuroleptic agent, a retrospective review of clinical trials of this drug might possibly reveal some points of interest.Numerous uncontrolled studies of the clinical effects of haloperidol, from various parts of Europe and the British Commonwealth show much conformity.All investigators agree on the efficacy of the drug against mania and states of acute agitation.Bohacek (1964) collected information on about 100 cases of mania treated with haloperidol, showing satisfactory results in more than 90 per cent, which is in accordance with the author's own finding.In a review of 39 clinical studies from 11 European countries comprising more than 500 manic patients, excellent results were reported in 78 per cent and good results in a further 15 per cent, totalling 93 per cent of the cases treated. The only phenothiazine derivative with which corresponding results are reported is thioproperazine (Majeptil), but with more frequent and severe side-effects.