 To date, there is no published report to examine D2 receptor occupancy of ziprasidone 24 hours after the last dose in patients with schizophrenia. This study will provide information on 24-hour time course of D2 occupancy of this drug, with which the dissociation between peripheral and central kinetics of this drug will be discussed. The results of this study will also test the feasibility of once daily dosing of ziprasidone, which will directly serve to guide physicians in clinical practice. Furthermore, the findings of this study will elucidate the relationship between D2 receptor occupancy and long-term outcome. 