Clozapine was initially studied in comparison with haloperidol.7 Clozapine was superior to haloperidol on all measures of psychosis and reduced both positive and negative symptoms. Clozapine produced more drowsiness and salivation, whereas haloperidol caused more insomnia. No cases of agranulocytosis were observed, but five patients developed neutropenia and three patients developed electroencephalographic abnormalities while on clozapine. One third of the clozapine group had to be discontinued due to adverse effects.