Abstract： BACKGROUND: Delirium is an acute organic brain syndrome caused by various reasons, and it is common in elderly patients. Antipsychotics treatment is an important method to control delirium.OBJECTIVE: To observe the efficacy of new antipsychotic agent of olanzapine and the traditional antipsychotic agent of haloperidol in treating senile delirium.DESIGN: A randomized controlled observation. SETTING: Mental Health Center, the First Affiliated Hospital of Chongqing University of Medical Sciences.PARTICIPANTS: Totally 175 inpatients with senile delirium were selected from the First Affiliated Hospital of Chongqing University of Medical Sciences from September 2001 to September 2003, they were randomly divided into olanzapine treatment group (n=74), haloperidol treatment group (n=72) and a control group(n=29). There were 111 males (63.4%) and 64 females (36.6%). Delirium had occurred for a duration of 30 minutes to 17 days, with an average of (3.02±2.71) days. The enrolled patients were classified according to the etiological factors of delirium: metabolic (n=68), toxic (n=47), structural (n=25) and infectious (n=35).METHODS: Different treatments were used in different groups. Control group (n=29): The patients were only given somatic treatment aiming at delirium, and not any drug for central nervous system was used. Olanzapine group (n=74): Besides the somatic treatment aiming at delirium, the patients were given olanzapine (Zyprexa, produced by Eli Lilly and Company,5 mg/tablet) taken orally or sublingually (fasted patients), the initial dosage was 1.25-2.5 mg per day, and then adjusted to 1.25-20 mg per day. Haloperidol group (n=72): Besides the somatic treatment aiming at delirium, they were treated with intramuscular injection of haloperidol (2.5-10 mg per day). The effects were prospectively observed for 1 week.The scores were observed before enrollment and at 1-7 days respectively,the severity of mental disorder and amelioration were evaluated by the clinical global impression scale-severity of illness (CGI-SI) and global improvement item of clinical global impression scale (CGI-GI). The dosage and time of administration was taken as the dosage and time to take effect when the CGI-SI baseline scores decreased by more than 1 point.MAIN OUTCOME MEASURES: The severity of mental disorder and amelioration were observed.RESULTS: ① The scores of CGI-SI after treatment were significantly decreased in the olanzapine group, haloperidol group and control group, and there were significant differences (P ＜ 0.01). ② The rates of marked effect in the three groups were 82.4%, 87.5% and 31.0%, respectively, and those in the two treatment groups were significantly different from that in the control group (P ＜ 0.01). ③ Both olanzapine and haloperidol began to take effect at small dosages, and it was the fasted in the olanzapine group, followed by the haloperidol group, and slowest in the control group.CONCLUSION: Olanzapine and haloperidol have similar effects in treating senile delirium. However, olanzapine is faster to take effect than haloperidol.