Objective: Pharmacotherapy including mood stabilizers and antipsychotics are frequently used in bipolar disorder (BD); however, the lack of consensus regarding the definition of polypharmacy hinders conducting comparative studies across different settings and countries. Research on Asian Prescription Pattern (REAP) is the largest and the longest lasting international collaborative research in psychiatry in Asia. The objective of REAP BD was to investigate the prescription patterns of psychotropic medications across Asian countries. The rates of polypharmacy and psychotropic drug load were also analyzed. Methods: The data collection was web-based. Prescription patterns were categorized as (1) mood stabilizer monotherapy: one mood stabilizer; (2) antipsychotic monotherapy: one antipsychotic; (3) simple polypharmacy: one mood stabilizer and one antipsychotic; and (4) complex polypharmacy: ≥ 2 mood stabilizers or/and antipsychotics. The psychotropic drug load in each patient was calculated using the defined daily dose method. Results: Among 2003 patients with BD (52.1% female, 42.4 years) from 12 countries, 1,619 (80.8%) patients received mood stabilizers, 1,644 (82.14%) received antipsychotics, and 424 (21.2%) received antidepressants, with 14.7% mood stabilizer monotherapy, 13.4% antipsychotic monotherapy, 48.9% simple polypharmacy, 20.3% complex polypharmacy, and 2.6% other therapy. The average psychotropic drug load was 2.05 ± 1.40. Results varied widely between countries. Conclusion: Over 70% of psychotropic regimens involved polypharmacy, which accords with the high prevalence of polypharmacy in BD under a permissive criterion (2 or more core psychotropic drugs) worldwide. Notably, ≥ 80% of our sample received antipsychotics, which may indicate an increasing trend in antipsychotic use for BD treatment.