UDI stands for Unique Device Identification, which is a system intended to assign a unique identifier to medical devices within the United States, Europe, China, South Korea, Saudi Arabia, and Taiwan. The UDI system assigns a unique numeric or alphanumeric code to each medical device, which generally consists of a device identifier (DI) and a production identifier (PI) . The DI is a mandatory, fixed portion of a UDI that identifies the labeler and the specific version or model of a device, while the PI identifies the unit of device production and, if applicable, the packaged devices. The UDI system is being implemented in phases to ensure a smooth implementation and to spread the costs and burdens of implementation over time.

The UDI is expected to improve patient safety by helping to identify counterfeit products and by improving the ability of staff to distinguish between devices that are similar in appearance but serve different functions. It is also expected to facilitate and improve the recall process and create efficiencies within the medical system. The UDI system increases traceability and enables both medical device manufacturers and FDA officials to respond quickly in the event patient safety is at risk due to a certain device issue.

In most instances, the labeler is the device manufacturer, but the labeler may be a specification developer, a single-use device reprocessor, a convenience kit assembler, a repackager, or a relabeler. The UDI system is governed by Section 519(f) of the Federal Food, Drug, and Cosmetic Act (the FD&C Act) and Section 614 of the Food and Drug Administration Safety and Innovation Act (FDASIA) .

Overall, the UDI system is an important tool for improving patient safety and modernizing device postmarket surveillance.