Purpose: Breast cancer (BC) treatment has shifted from chemotherapy to targeted therapy.Several targeted agents have demonstrated an improvement in survival. Given that national healthcare resources were correlated with the cancer mortality-to-incidence ratio, we compared access to BC drugs in Thailand with that in other Asian countries. Methods: BC experts involved in the Breast International Group (BIG)-Asia in six representative groups for countries or special administrative region (SAR) in Asia (Hong Kong SAR, Japan, Korea, Taiwan, Thailand, and Singapore) were invited to participate in the survey. The questionnaire addressed national health reimbursement schemes, molecular testing for early BC (EBC), availability and accessibility of BC drugs. Accessibility and reimbursement of the drugs were reported based on their listing as essential medicines in the World Health Organization Model List of Essential Medicines (WHO-EML) and their nomination as effective drugs in the European Society for Medical Oncology-Magnitude of Clinical Benefit Scale (ESMO-MCBS). The study was approved by all participating BIG-Asia organizations in November 2021. Results: Genomic tests for EBC were non-reimbursable in all surveyed territories.Reimbursement and co-payment of BC drugs vary between and within these regions (particularly Thailand). Most drugs in the WHO-EML and ESMO-MCBS (A/B for EBC and 4/5 for advanced BC) were accessible in all surveyed territories. However, the accessibility of effective but costly WHO-EML and ESMO-MCBS drugs was not uniform in Thailand. There was an evident disparity for individuals covered by the Thai Social Security/Universal Health Coverage schemes. Conclusion Essential BC drugs are generally accessible in selected BIG-Asia countries or SAR. There is a disparity in accessing high-cost drugs in Thailand compared with other Asian territories.