In thousands of communities across the United States, drinking water is contaminated with chemicals known as perfluoroalkyl and polyfluoroalkyl substances (PFAS). PFAS are used in a wide range of products, such as non-stick cookware, water and stain repellent fabrics, and fire-fighting foam, because they have properties that repel oil and water, reduce friction, and resist temperature changes. PFAS can leak into the environment where they are made, used, disposed of, or spilled. PFAS exposure has been linked to a number of adverse health effects including certain cancers, thyroid dysfunction, changes in cholesterol, and small reductions in birth weight.This report recommends that the Centers for Disease Control and Prevention (CDC) update its clinical guidance to advise clinicians to offer PFAS blood testing to patients who are likely to have a history of elevated exposure, such as those with occupational exposures or those who live in areas known to be contaminated. If testing reveals PFAS levels associated with an increased risk of adverse effects, patients should receive regular screenings and monitoring for these and other health impacts. Guidance on PFAS Exposure, Testing, and Clinical Follow-Up recommends that the CDC, Agency for Toxic Substances and Disease Registry (ATSDR), and public health departments support clinicians by creating educational materials on PFAS exposure, potential health effects, the limitations of testing, and the benefits and harms of testing.