Objective Little is known about the pattern of QT interval (QTc) prolongation in Asian patients with schizophrenia. This study examined trends of QTc prolongation in schizophrenia inpatients in six Asian countries and territories between 2004 and 2008/2009 and its independent demographic and clinical correlates. Method Data on 3482 hospitalized schizophrenia patients (2004 = 1826 and 2008/2009 = 1656) in six Asian countries and territories were collected by either chart review or interviews during a 1-month period. Patients' sociodemographic and clinical characteristics, prescriptions of psychotropic drugs, and QTc interval were recorded using a standardized protocol and data collection procedure. Results The frequency of QTc prolongation (>456 ms) was 2.4% in the whole sample, decreasing from 3.1% in 2004 to 1.6% in 2008/2009 (p = 0.004) with wide intercountry variations. However, this decreased trend was driven by decreased QTc prolongation detected in China and Hong Kong (both p-values < 0.05). Multiple logistic regression analysis of the whole sample revealed that patients having more likely to have an illness lasting longer than 5 years and received antipsychotics classified as list-1 drugs according to the Arizona Centre for Education and Research on Therapeutics. Compared with 2004, patients in 2008/2009 were less likely to have QTc prolongation. Thioridazine caused QTc prolongation most frequently (odds ratio (OR) 4.4; 95% confidence interval (CI) 1.2-15.2), followed by sulpiride (OR 2.4; 95% CI 1.3-4.5), clozapine (OR 2.4; 95% CI 1.4-4.2), and chlorpromazine (OR 1.9; 95% CI 1.07-3.5). Conclusions Frequency of QTc prolongation was low in Asian patients with schizophrenia. QTc prolongation in schizophrenia decreased in China and Hong Kong between 2004 and 2008/2009 but increased in Taiwan over the same period, remaining low in the other countries.