This article provides a summary of the Unique Device Identifier (UDI) requirements. UDI will be applicable to all manufacturers of medical devices in the EU. If you would like to know more about the UDI requirements, please take a look at the video below.

The video is an extract from the online course Introduction to the Medical Device Regulation (EU) 2017/745 which covers how manufacturers of medical devices can effectively implement the MDR requirements.

Disclaimer: Please note, the UDI requirements in the EU are not identical to the UDI requirements of other markets, like the US market.

What is BUDI – Basic UDI-DI?

Basic UDI-DI is a unique UDI requirement in the EU, so there are no corresponding codes available outside the EU. This has caused and still continues to cause some confusion.

Basic UDI-DI is a kind of collective code used to cover devices with the same or similar:

  • intended purpose,
  • risk class,
  • essential design, and
  • manufacturing characteristics.

Basic UDI-DI will NOT be found on any devices or packaging. It is only used as a collective term for grouping devices and reporting in EUDAMED.

The concept of UDI

The purpose of the Basic UDI-DI is to act as the main key in EUDAMED and for relevant documentation like certificates, declarations of conformity, technical documentation, Periodic Safety Update Reports (SSCP) as well as certificates of free sales.


One Basic UDI-DI can cover several UDIs, but a UDI cannot be included in several Basic UDI-DIs.

The actual UDI is split into two parts:

  • The UDI-DI where the DI stands for Device Identifier
  • The UDI-PI where the PI stands for Production Identifier

The UDI-DI part is mandatory for ALL medical devices, while UDI-PI is only applicable where labelling must include production-related information, for example:

  • the lot number,
  • serial number,
  • software release, or
  • when the expiry date must be clear.

If the expiry date or manufacturing date is crucial for a device, independent of class, a UDI-PI is required. Any essential information on the label that is defined during production will require a UDI-PI.

The UDI requirements are a bit spread out through the MDR but the main article for UDI is article 27.

Machine-readable code design

The Basic UDI-DI is an alphanumeric code that need to be readable to humans, a Human Readable Interface, or short HRI. BUDI’s do not need a barcode.

Unique Device Identification system

The UDI, including the UDI-DI and UDI-PI, must be readable to both humans and machines. AIDC (Automatic identification and data capture) is a machine-readable interface. Examples of AIDCs include:

  • 2D barcodes,
  • dot-matrix codes
  • biometrics, and
  • RFID.

The PI part needs more data, which means a longer code. Fitting a large barcode on a product package can pose a challenge. Luckily, there are dot matrix codes available to use when a 2D barcode is too long.

BUDI is for example used for certificates, as well as registering the actual device in EUDAMED together with the UDI-DI. They are the static parts of the UDI system, meaning, they will stay the same unless a device is changed. The MDCG 2018-1 explains when you need to change the UDI-DI and the relationship to the Basic UDI-DI.

The manufacturer and UDI

The UDI shall be placed on the product by the manufacturer. That is why it is also a requirement that the manufacturer integrates the assignment and application of the UDI in their QMS.

There is an MDCG (2021-19) endorsed document that explains the UDI requirements in relation to the manufacturer’s QMS. Notified bodies follow this guideline strictly and it is recommended that you read it.

Both the BUDIs and the UDIs shall be unique to the manufacturer and must be obtained from a designated issuing entity according to their nomenclature. The currently available issuing entities are:

  • GS1,
  • HIBCC,
  • AISBL, and
  • IFA (Informationsstelle für Arzneispezialitäten)

UDI-DI – A unique code

The UDI-DI must be unique to a manufacturer and device. Simply put, the UDI-DI somewhat corresponds to the order number that you will use for selling the devices, also known as the REF number.

This does not mean that order numbers or REF numbers need to be replaced with the actual UDI-DI code, but they must be linked internally and in EUDAMED.

This also means that if the same product is offered in different quantities, for example, a 5-pack or a 20-pack, with different order numbers, they need to have different UDI-DIs for the different packages, meaning, one UDI-DI for the actual device and another UDI-DI for the sales packages if sold in different quantities. Please note, shipping containers are exempt from UDI requirements.


The UDI carrier and UDI-PI

The UDI carrier should not include the Basic UDI-DI, only the UDI-DI and, if applicable, the UDI-PI. The UDI carrier must also be readable both to humans and machines.

The UDI should be placed on the actual device, and if that is not possible, it should be placed on the packaging.

The PI, Production Identifier, is part of the UDI code. It is dynamic and used to identify the specific data related to the production of that specific device. For example, serial numbers, lot number, software identification, manufacturing or expiry date or both types of date.

UDI-PIs in AIDC are not required to appear on packaging for products strictly intended for retail sale. On the other hand, this is crucial for active implantable medical devices. Their PI requires a serial number on unit level.

When to comply with UDI regulations

The dates of when the UDI carrier must be on all devices can be seen below. The upper row is for ”normal” devices and the bottom row is for devices that are intended to be reused, like surgical instruments.

MDCG 2021-19

The dates for these re-usable devices shown here explain when the actual device needs to have the UDI carrier on them. Essentially, this means that the device itself should be marked with the UDI, not just the label.

The UDI – More than just a barcode

By now it is clear that the UDI is more than just a barcode. The majority of the MDR requirements are collected in article 27 and annex VI, but the annex can be considered a bit messy and not the best part of the MDR.

The MDR needs clarification on many things in relation to UDI, so the MDCG has been busy issuing guidance documents on this subject.

To stay up to date when new or updated guidelines are published, please visit the MDCG website frequently. Software and procedure packages and some other devices have specific guidelines published by the MDCG.

If you found this article helpful, do check out our articles archive.

Would you like to know more about the Medical Device Regulation?

If you want to know more about understanding the European regulation for medical devices, take a look at our online Introduction to the Medical Device Regulation (EU) 2017/745 course. This online course is an in-depth overview of the Medical Device Regulation according to (EU) 2017/745 as well as related guidances, like MDCG, and how to apply to a notified body for conformity assessment.

It is suitable for anyone working with regulatory questions, such as RA and QA engineers, PRRC or management.

Pontus Gedda

Pontus Gedda

Pontus Gedda is a dedicated medical device specialist that has worked both in the industry, as a design engineer and project manager, and in the notified body world as a medical device lead auditor and manager.

He has vast experience in the MDR and its implementation thru hands-on experience from implementing the MDR at a notified body and leading that notified body through a joint assessment and getting designated as an MDR notified body.

He was a senior manager at a notified body during the transition from MDD to MDR and also a member of the NB-MED group.