 The Health Insurance Review and Assessment Service, HERA, collects claims data from healthcare service providers to help researchers better understand the healthcare system. HERA has developed the patient samples, which are extracted through a stratified randomized sampling process. These samples contain five tables, table 20 with demographic information, table 30 with details about healthcare services received, table 40 with diagnostics, table 53 with prescription information, and table of providers with provider information. Researchers can use these samples to gain insights into the healthcare system. This article was authored by Log Young Kim, G.A.E. Kim, and Song Yun Kim.