What is software as a medical device (SaMD)?

How it works

The International Medical Device Regulators Forum (IMDRF), a voluntary international group of medical device regulators, defines the term. The U.S. Food and Drug Administration (FDA) chaired the SaMD working group that IMDRF formed in 2013. It gives the forum's definition: software meant to serve one or more medical purposes without being part of a hardware medical device.

A key test is whether a hardware device needs the software to do its medical job. The FDA's examples of SaMD include:

• software that lets a smartphone display MRI images for diagnosis
• computer-aided detection software that processes images to help detect breast cancer
• treatment planning software that supplies information to a linear accelerator

Software that drives the motors of an infusion pump or runs closed-loop control in an implantable pacemaker is not SaMD.

How regulators rank the risk

The IMDRF risk framework, as the FDA describes it, puts SaMD in one of four categories, I to IV, set by two factors. One is the state of the patient's condition (critical, serious or non-serious). The other is how the output is used (to treat or diagnose, to drive clinical management or to inform it). Category IV, the highest, applies to software used to treat or diagnose in critical situations. The FDA calls the framework harmonized quality management principles for regulators to adopt within their own systems, not regulations.

Guidance endorsed by the European Union's Medical Device Coordination Group uses another term, medical device software. That covers software with a medical purpose, whether it is independent or drives or influences a device's use. The guidance, revised in June 2025 and not legally binding, says the EU classification rule for such software, Rule 11, was introduced partly to mirror the IMDRF approach. Under that rule, software that provides information used for diagnostic or therapeutic decisions is class IIa. Exceptions are decisions that could cause a serious deterioration in health or a surgical intervention (class IIb), or death or an irreversible deterioration (class III).

Where things stand in 2026

AI-based products come under the same device rules. The FDA says it does not regulate AI as such. It regulates medical devices, a term that includes software apart from certain functions excluded by law. The agency's page, dated September 22, 2026, says it had authorized more than 1,600 AI-enabled medical devices for the U.S. market as of that month.