This article discusses the conflicting requirements of and assertions made to the Food and DrugAdministration 510(k) approval process and the United States Patent and Trademark Office patent application process for a medical device. Generally, in a 510(k) submission, a company asserts that its device is a substantial equivalent of a predicate device. Conversely, in a patent application, a company asserts that its device is new and nonobvious over all prior art devices. This article explores the risks that arise for a company, whether as a patent holder or an accused patent infringer, because of assertions made as part of a 510(k) submission. The authors look at the possibility of using a 510(k) submission against a company to invalidate that company's patent, then examine the possibility of using a company's 510(k) submission to show infringement of another company's patent. They discuss how regulatory and patent counsel can work together to navigate both regulatory schemes to minimize associated risks-requiring credible arguments of substantial equivalence simultaneous with arguments of novelty and nonobviousness.