Experimental tests of whether an individual neuroleptic treatment for compensation of acute schizophrenic disorders is more effective and has fewer side effects than a standard therapy were performed under double-blind conditions. For this purpose, a group of 16 patients was treated with 10 mg haloperidol/day for the duration of 14 days, and another group of 16 patients was treated with 20 mg haloperidol/day for the same period. 16 patients of a third group were treated for 14 days with an individual haloperidol dose adapted to the psychopathological findings. Patients were randomly allocated to the treatment groups. The medication was laid down in accordance with the randomization plan without informing the ward staff and raters by a leading physician of the hospital who was not involved in the data collection in the investigation. The psychological findings were registered by means of the BPRS and the global appraisal by the doctor (CGI) on days 0, 7 and 14. Extrapyramidal side effects were registered by means of the Simpson scale on days 0, 7 and 14. A superiority of the individually adapted treatment over standardized treatment could be demonstrated neither for the therapeutic target parameters nor for the side effect variables. On the contrary, a tendency to superiority in the groups treated with fixed doses was found. The results are discussed in terms of their significance for treatment practice.