This Statistical Brief from the Agency for Healthcare Research and Quality presents national data from the Healthcare Cost and Utilization Project on rates and total costs of potentially preventable hospitalizations. Distribution of the total costs by payer is also examined. The study found that in 2006, nearly 4.4 million hospital admissions, totaling $30.8 billion in hospital costs, could have been potentially preventable with timely and effective ambulatory care or adequate patient self- management of the condition.