1. Butyrylperazine was administered to 20 patients at Manhattan State Hospital, New York City, and 26 patients at the University Psychiatric Clinic of Erlangen, West Germany.2. There were significant differences between both groups in (a) dosage requirements, (b) side effects, and (c) clinical results.3. It is suggested that genetic factors may play some role in explaining at least two of these findings (2a and b).Abstract Teaser