Fluphenazine decanoate and pipothiazine palmitate were compared concerning their effect and side-effects. 61 schizophrenic patients were treated up to 6 months in a multicenter double-blind trial. Assessments were made on day 0 and after 5, 10, 17 and 22 weeks of treatment using the AMP system. Pipothiazine palmitate was injected every 4th week and fluphenazine decanoate every 3rd week. The most often applied dosage was 100 mg pipothiazine palmitate and 25 or 37.5 mg fluphenazine decanoate. Data analysis of the AMP system at the symptom level showed the better antipsychotic effect of pipothiazine palmitate. A comparison between the two groups by means of analysis of covariance at the syndrome level showed no statistical significant differences between the effects of fluphenazine decanoate and pipothiazine palmitate.