© 2019, Springer Nature Switzerland AG. We propose the following definition of a medical device: “A contrivance designed and manufactured for use in healthcare, and not solely medicinal or nutritional.” Current regulatory classifications of medical devices are complex and designed primarily for regulators. We propose a simpler classification, based on (1) the site of application of the device, (2) the time scale of its use, and (3) whether it has an external power source. The regulation of medical devices is less well developed than the regulation of medicinal products, which it could follow more closely. In particular, devices that incorporate medicines should be required to meet the same regulatory standards as medicinal products. This would remove the anomaly that some delivery systems that incorporate medicines are classified as devices while other similar systems that deliver the same medicines are classified as medicinal products. Some improvements might also result from more widespread use of registries, such as those used for prosthetic joint replacements. Registries would allow both a prospective examination of the performance of high-risk devices and a retrospective analysis when signals from other sources of information suggest problems. Those who apply for a marketing authorization for a new device should have to assure regulators of its quality of manufacture, safety, and efficacy before licensing. Even the most straightforward device should be shown to be useable in practice. Trials on patients, or at least simulations of use in the real world, should be practicable for most devices.