The Food and Drug Administration regulates the sale and distribution of laboratory devices under a statutory and regulatory framework that is unfamiliar to most clinical laboratory scientists. In this article we briefly describe the criteria that are used to classify and review in vitro diagnostic devices. We discuss the similarities and differences between devices that are not subject to premarket review, and those that are required to undergo either a premarket application or premarket notification [510(k)] pathway. We then discuss the methods that the Food and Drug Administration uses to assess the performance of in vitro diagnostic devices in the marketplace as a component of the total life cycle approach to medical device regulation.