What Makes a Valid 510(k) Predicate Device? FDA Requirements Explained

The 510(k) pathway requires demonstrating substantial equivalence to a "legally marketed predicate device." Those four words carry specific legal and regulatory meaning — and misunderstanding what qualifies as a predicate is one of the most common and costly mistakes in 510(k) preparation.

What "legally marketed" means

A predicate must have been legally marketed in the United States — not just anywhere in the world. CE-marked devices marketed in Europe are not valid predicates. Devices marketed in Canada, Japan, or other markets under their respective regulatory frameworks are not valid predicates unless they also hold a US clearance.

The most straightforward valid predicates are devices with a K-number — a 510(k) clearance — issued by FDA. The K-number confirms that FDA reviewed the device and found it substantially equivalent to another legally marketed device, establishing a clear legal marketing history.

Preamendment devices as predicates

Devices that were legally marketed in the United States before May 28, 1976 (the date of the Medical Device Amendments) are considered preamendment devices. Because they predate the 510(k) program, they don't have K-numbers, but they can serve as predicates.

Establishing a preamendment predicate requires documenting that the specific device type was commercially distributed in the United States before that date. This typically requires published literature, trade publications, patents, or other documentation from before 1976. For most modern device categories, there are cleared 510(k) predicates that are easier to identify and document — preamendment predicates are most relevant for long-established device types.

The predicate chain

Your predicate device itself was cleared through a 510(k) — which means it cited its own predicate. That predicate cited another predicate, and so on, forming a predicate chain that ultimately traces back to either a preamendment device or a De Novo-classified device.

FDA reviewers sometimes trace the predicate chain to confirm that each link in the chain is valid and that the device types remain consistent throughout. A predicate chain that breaks — for example, where one link cites a device in a fundamentally different device category — can undermine your predicate argument even if your immediate predicate looks appropriate.

Recalled and withdrawn predicates

A predicate device that has been subject to a Class I recall does not automatically become invalid as a predicate. However, if the recall was initiated because the device itself raised safety concerns (rather than a manufacturing issue), using it as a predicate creates a problematic argument — you would be claiming equivalence to a device that was removed from the market due to safety issues.

FDA does not prohibit recalled devices from serving as predicates, but reviewers will scrutinize the recall history. If your predicate has a recall, understand the reason and be prepared to address it in your submission.

Confirming predicate validity before you start testing

Before investing in performance testing, verify that your chosen predicate is valid. Check the FDA 510(k) database to confirm the device has a K-number, the clearance is still active, and the intended use matches your device. Check the FDA recall database to see if the predicate has any active Class I or Class II recalls.

A week of predicate validation research before testing begins prevents the scenario of completing testing only to discover the predicate is invalid or was recently recalled.