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Predicate devices

A predicate device is a legally marketed device that a new device is compared against in a 510(k). The comparison is the submission. FDA does not assess a new device on its own merits in this pathway; it assesses whether the device is substantially equivalent to one already on the market. This makes the choice of predicate the decision the whole submission rests on.

21 CFR 807.92(a)(3); 21 CFR 807.100(b); FD&C Act 513(i)

At a glance

Definition	A legally marketed device to which a new device may be compared for a determination of substantial equivalence.
The regulation	21 CFR 807.92(a)(3). Note it is not 807.87, which does not mention predicates.
What counts as legally marketed	Marketed before 28 May 1976; reclassified from Class III to Class II or I; found substantially equivalent through a 510(k); or granted through De Novo.
Can a withdrawn device be used?	Yes. FDA states an applicant may claim equivalence to a device no longer marketed.
Can a recalled device be used?	Usually yes. See the trap below — only two things legally disqualify a predicate.
More than one predicate?	Permitted. FDA recommends identifying a primary predicate and keeping the number to the minimum necessary.
Reference device	Not a predicate. It supports methodology only, and only after Decision Point 4.
Split predicate	Inconsistent with the 510(k) standard. See below.

What qualifies as a predicate

The regulation defines a predicate as a device that was legally marketed before 28 May 1976, or a device reclassified from Class III to Class II or I, or a device found substantially equivalent through the 510(k) process.

FDA adds a fourth category on its own pages that the regulation does not contain, because it predates the route: a device granted marketing authorization through the De Novo process, where that device is not itself exempt from premarket notification.

"Legally marketed" carries weight. FDA states that the predicate cannot be one that is or was in violation of the FD&C Act.

Only two things legally disqualify a predicate

A device may not be used as a predicate if it was removed from the market at the initiative of the Commissioner of Food and Drugs, or if it was determined to be misbranded or adulterated by a judicial order. Those are the only two statutory bars, at FD&C Act 513(i)(2) and 21 CFR 807.100(b)(3).

A voluntary recall is not one of them. Neither is withdrawal from the market for commercial reasons.

FDA does recommend avoiding a predicate that has been subject to a design-related recall, on the reasoning that such a recall can indicate a fundamental flaw with the design as cleared. That recommendation appears in a guidance which, as of August 2026, remains in draft and states on its face that it contains non-binding recommendations.

The practical position: a recalled device can usually still serve as a predicate, and a careful submitter checks the FDA recall database before choosing one anyway.

Multiple predicates

More than one predicate may be cited. FDA permits this when combining features from devices with the same intended use, or when seeking more than one indication for use. Each predicate must have the same intended use as the new device. FDA recommends identifying a primary predicate and limiting the rest to the minimum necessary.

Reference device

A reference device is a legally marketed device used to provide scientific or technical information, such as a test methodology, that helps address a new technological characteristic. FDA states plainly that reference devices are not predicate devices. A reference device cannot be used to answer the first four decision points in FDA's substantial equivalence flowchart.

Split predicate

A split predicate means using one device for intended use and a different device for technological characteristics. FDA's position is that this is inconsistent with the 510(k) regulatory standard. FDA must be able to work through decision points 1 to 4 using a single predicate.

Reference device and split predicate are both guidance constructs. Neither term appears in the statute or in 21 CFR Part 807.

Questions people ask

Where do we search for a predicate?

The FDA 510(k) premarket notification database holds every clearance FDA has issued. It is public and searchable by product code, applicant, device name and decision date.

Can we use a competitor's device as our predicate?

Yes. A predicate does not have to be your own device, and the predicate holder is not notified and has no right of objection. The cleared device becomes part of the public record when FDA clears it.

What if the closest device has a slightly different intended use?

Then it is not a valid predicate for that comparison. Same intended use is the first substantive test, and a difference there ends the 510(k) route rather than adding work to it. Additional testing does not repair it.

Does a newer predicate carry more weight than an older one?

No. Any legally marketed device meeting the definition may be used. Recently cleared devices are often chosen because their submissions reflect current FDA expectations on testing, but age itself is not a criterion.

How many predicates should a submission cite?

FDA recommends the minimum number necessary, with one clearly identified as primary. More predicates means more comparisons for a reviewer to work through, and every one of them is a place the submission can be questioned.