Abstract: This paper provides an introduction to laboratory databases established by Taiwan National Health Insurance Administration (NHIA) since 2015 and released for research since June 2017. The National Health Insurance (NHI) is a government-run single-payer program introduced in 1995 that now covers more than 99% of 23 million Taiwanese citizens. To prevent duplication of medication prescriptions and laboratory test and examination prescriptions, contracted health care providers are required to upload the results of laboratory tests and reports of examinations to the NHIA. The cumulative number of laboratory test results was 5.64 billion from January 2015 to the end of August 2020 for 602 types of test. There are 35 variables for each laboratory test result stored in the databases that can be used for research. However, different hospitals might use different format in reporting the results. The researchers therefore have to develop algorithms to include and exclude incompatible