The design of medical devices is generally a complex and demanding process, often with high potential risk to patients if the device does not function as envisioned. The initial challenge is to correctly capture clinical requirements and to manipulate and to translate these requirements into a technically competent and reliable device that can and will be used effectively in the clinical environment. Successful medical device design includes active consideration of the human factors aspects of user needs and an adequate system safety and risk analysis. Instructions for use including installation and service and manufacturing must also be considered throughout the design cycle. Modification of existing designs whether by the original manufacturer or by the device owner, or a third party, requires particular care so that carefully made decisions during the initial design cycle are not undone by a hastily conceived fix or upgrade. The reuse of devices labeled by the manufacturer as single use only is one example of a “modification” that has received considerable attention and FDA scrutiny. The design process is subject to FDA regulation under the Design Controls section of the Quality Systems Regulations. Compliance with these regulations requires broad knowledge of them by everyone on the design team.