Do information frictions in health care markets lead to higher prices and price dispersion? Focusing on medical imaging procedures, this paper examines the equilibrium effect of a unique statewide price transparency website. Price information leads to a shift to lower-cost providers, especially for patients subject to a deductible. Furthermore, supply-side effects play a significant role in the long run, benefiting all insured individuals. Supply-side effects reduce price dispersion and are especially relevant in concentrated markets. These effects are important given that high prices are thought to be a primary cause of high private health care spending.