The development of medical-device technology is constrained by the financial and ethical considerations of animal testing and clinical trials. Organ-on-a-chip systems are being developed to speed up drug development, yet there has been little recognition or support for the use of this technology in the development and testing of medical devices. In this Perspective, we introduce the concept of medical-device-on-a-chip (MDoC), highlight possible applications and discuss the potential of microfluidic high-throughput technologies for achieving significant time and cost savings over conventional testing. Rather than testing an entire macroscale device, a MDoC has the ability to recapitulate biological function in a physiome associated with medical-device use and to test interactions with device components. In the clinic, MDoCs could also incorporate individual human samples for personalized diagnostics. We also review research towards the integration of key elements of organ-on-a-chip technologies with medical-device testing. Medical devices are indispensable in nearly every aspect of healthcare. Advances in medical devices and diagnostics in the past 30 years have increased life expectancy by five years and reduced fatalities from common diseases by more than half1. They have also decreased the cost of medicine and reduced the duration of hospital stays by 58% (ref. 1). Restoring vision with visual prostheses, restoring hearing with cochlear implants, and improving mobility with orthopaedic implants or neural implants are among the achievements of modern medical devices (a definition of the term ‘medical devices’ can be found in the Federal Food, Drug, and Cosmetic Act, US Code, Title 21, § 321(h)). Although advances in biomedical engineering will help to continue this transformation of medicine in the twenty-first century, the rapidly escalating costs of developing and marketing medical devices create a disincentive for innovative technology with a greater risk of failure. A good metric for this changing entrepreneurial environment is found in venture capital, where the share of medical technology has fallen from 13% in 1992 to 4% in 2014 (ref. 2).