BV data are reference data that have many applications in laboratory medicine. The data describe the variability of clinically important measurands around homeostatic set points within subjects (CVI) and between subjects (CVG). The availability of well characterised data enables the interpretation of laboratory results in clinical settings and can be used to define analytical performance specifications (APS) and other applications. The literature describing studies of BV stretches back over 45 years. Reviews of BV data identify widely varying estimates for many measurands, calling for a new approach to deliver robust BV estimates for safe clinical application. On this background, the Working Group on BV and the Task Group on the Biological Variation Database have developed a standard for evaluating studies on BV; the Biological Variation Data Critical Appraisal Checklist (BIVAC), a Minimum Dataset for BV studies and a meta-analysis approach for delivery of global BV estimates. These tools are used to populate the EFLM Biological Variation Database.