Purpose Little is known regarding the trend of polypharmacy in Asia. We used data from 5 Asian countries to examine the patterns of antidepressant (AD) prescription and trends of psychotropic polypharmacy over time. Methods We used the cross-sectional, pharmacoepidemiological data from 2004 and 2013 REAP-AD (Research on Asian Psychotropic Prescription Patterns for Antidepressants) to examine the patterns of AD prescriptions in clinical settings in China, Japan, Korea, Singapore, and Taiwan. We compared the trend in polypharmacy (ie, concomitant use of ≥2 classes of psychotropic) among individuals receiving AD prescriptions in 2004 and 2013 using multivariable logistic regression models in different diagnostic categories. Results The proportion of patients with psychotropic polypharmacy decreased from 2004 to 2013 in all 3 diagnostic categories, including mood disorders (adjusted odds ratio [aOR], 0.44 [0.35-0.56]; P < 0.001), anxiety disorders (aOR, 0.58 [0.36-0.94]; P = 0.028), and psychotic disorders (aOR, 0.18 [0.05-0.60]; P = 0.006). Among individuals with AD prescriptions, concomitant use of anxiolytics (including sedative-hypnotics) decreased in patients with mood disorders (aOR, 0.34 [0.27-0.42]; P < 0.001) and anxiety disorders (aOR, 0.43 [0.27-0.67]; P < 0.001). In contrast, concomitant use of antipsychotics in patients with mood disorders increased (aOR, 1.43 [1.15-1.77]; P = 0.001), and concomitant use of mood stabilizers in patients with psychotic disorders also increased (aOR, 3.49 [1.50-8.14]; P = 0.004). Conclusions This is the first study examining trends in psychotropic polypharmacy in East Asia. We found a generally decreasing trend of psychotropic polypharmacy in contrast to the increasing trend reported from Western countries. These findings could offer significant implications for health system reform or policy making.