The relationship between higher procedure volumes and medical outcomes has generated recommendations for greater use of high-volume hospitals, with research and advocacy on this issue intensifying during the 1990s. Despite this interest, the trends presented here showed only limited changes between 1995 and 2002. For a number of services, less than half of patients received care at high-volume hospitals, and for several services, there was a surprising decline in the proportion at high-volume hospitals. Trends in the rate of high-volume hospital use appeared to be associated with trends in aggregate volume, at the same time that there were only modest changes in either patient use of high-volume hospitals or the number of hospitals offering these services. These trends suggested the importance of research on factors that affect patient choices, hospital decisions, and payer incentives concerning hospital use, especially in the context of declining aggregate procedure volumes.