Medical DevicesLast reviewed April 2026

Substantial Equivalence(SE)

The FDA determination that a new medical device is as safe and effective as a legally marketed predicate device, allowing 510(k) clearance.

Usage Examples

The 510(k) cited two predicates to establish substantial equivalence across both intended use and technological characteristics.
FDA found the new catheter substantially equivalent based on bench performance data and matched indications.
A Not Substantially Equivalent decision required the sponsor to pivot to a De Novo classification request.

What is SE?

Substantial equivalence is the core legal and scientific standard a 510(k) submission must meet for FDA clearance. A device is substantially equivalent to a predicate if it has the same intended use, and either the same technological characteristics, or different characteristics that do not raise new questions of safety and effectiveness and demonstrate comparable performance.

FDA evaluates substantial equivalence through a structured comparison covering intended use, indications for use, target population, technological characteristics (design, materials, energy source, operating principles), and performance data. Weak or missing evidence in any dimension can result in a Not Substantially Equivalent (NSE) decision, pushing the sponsor toward the De Novo pathway or a PMA.

Multi-predicate strategies are permitted when no single predicate covers all characteristics, but FDA scrutinizes split predicate approaches that blend intended use from one device with technology from another — this pattern frequently triggers deficiency questions during review.

Regulatory Context

This term appears most often in medical devices workflows where submission quality, regulatory evidence, and audit readiness depend on consistent language. It is commonly referenced alongside 21 CFR 807, FDCA SECTION 513I.

FDA CDRHEMAHealth Canada

When This Matters

The 510(k) cited two predicates to establish substantial equivalence across both intended use and technological characteristics.
FDA found the new catheter substantially equivalent based on bench performance data and matched indications.
A Not Substantially Equivalent decision required the sponsor to pivot to a De Novo classification request.

Common Mistakes

Using drug-only submission assumptions for device regulatory pathways.
Ignoring post-market obligations in pre-market planning.
Weak predicate and classification rationale in dossier narratives.

Related Regulations

21 CFR 807FDCA SECTION 513I

Frequently Asked Questions

An NSE determination means the 510(k) pathway is closed for that device. The sponsor can resubmit with a stronger predicate argument, file a De Novo classification request (if no predicate exists), or pursue PMA approval.

No. The predicate must be legally marketed in the United States — specifically, a device that was either cleared via 510(k), classified via De Novo, or legally marketed before May 28, 1976 (preamendments device).

When technological characteristics differ from the predicate, FDA requires performance data (typically bench testing, sometimes clinical) demonstrating the differences do not raise new safety or effectiveness questions. The data must address each specific difference identified.