This Practice Note provides an overview of the regulatory framework set out by Directive 93/42/EEC on medical devices (MDD), Directive 90/385/EEC on active implantable medical devices (AIMDD), which were applicable until 25 May 2021, and Directive 98/79/EC on in vitro diagnostic medical devices (IVDD), which applied until 25 May 2022, altogether the MD Directives. The MD Directives still are relevant to ‘legacy’ devices which were authorised in accordance with them for placement on the EEA market before the new regulatory regime began its application. The MD Directives will continue to be relevant as a reference for a number of years in relation to certain legacy devices for varying time periods in accordance with transitional provisions. This Practice Note explains how devices were classified, assessed (by completion of a conformity assessment) and CE marked under the MD Directives. It also considers the advertising and promotion of medical devices, counterfeit medical devices, 3D printing and mobile health.