Data are presented from a multidimensional, longitudinal study in 10 acute schizophrenics which indicate that the addition of benztropine to haloperidol reversed the course of some of the therapeutic changes. The nontherapeutic interaction was selective involving what may be called social avoidance behavior but not the cognitive integrative dysfunctions. It is suggested that neuroleptic effects on social avoidance behavior in schizophrenics may be mediated through a cholinergic system. Caution is advised against routine use of antiparkinsonism agents with neuroleptics.