 The Health Insurance Review and Assessment Service, HERA, collects claims data from health care service providers to reimburse them for services provided to patients. To improve accessibility of this data for health care service researchers, HERA has developed patient samples using a stratified randomized sampling method, consisting of five tables containing general and specific information on health care services, diagnostic information, outpatient prescriptions, and providers. Researchers can apply to use the patient sample data via HERA's website. This article was authored by Log Young Kim, GAE Kim, and Song Yun Kim.