Patients suffering from acute schizophrenia are subjected to treatment according to different therapy standards, depending on the individual hospital. Hence, the present study aimed at a comparative investigation of the effects and side effects of fluphenazine dihydrochloride administered to 51 acutely diseased schizophrenics via the intravenous, intramuscular and oral routes. It was also interesting to record the assessment of efficacy, painfulness and, as the case may be, repeated selection of the form of application concerned, by the patients themselves. Finally, we also investigated the relations between the age of the patients, duration of previous hospitalisation, and the effects achieved with the three application forms. Documentation was effected via the following examination instruments described and recommended by the National Institute of Mental Health (NIMH), USA; CGI, BPRS, Dotes, APDI and PTR.