A total of 13 patients with drug-induced psychosis in Parkinson's disease were treated with two non-classical neuroleptics-clozapine and fluperlapine. Patients mainly complained about severe hallucinatory symptoms and different degrees of paranoid delusions. Complete relief was observed in 8 patients, moderate improvement in 3 and no effects in 2. Parkinsonian disability did not increase under neuroleptic medication with clozapine and fluperlapine, but could be ameliorated by additional L-dopa or bromocriptine medication. The non-classical neuroleptics employed are dopamine D2 blocking agents with a preferential binding to mesolimbic, mesocortical and hippocampal D2 receptors and no substantial binding to striatal dopamine receptors. Restricted use of these two neuroleptics is necessitated because of the danger of agranulocytosis.