Recently, there has been increasing interest in alternative Volume Performance Standards centered around the hospital medical staff. Using a national sample of Medicare claims, this paper analyzes growth in Medicare inpatient physician charges per admission between 1986 and 1989, by specially, type of service, and type of hospital. Although growing more slowly than outpatient services, inpatient physician service volume and intensity growth is substantial. Inpatient physician services grew at an annual rate of 8.3%-31% of which was attributable to prices, 27% to case mix, and 41% to volume and intensity. Services provided by cardiologists, gastroenterologists, and other medical specialists demonstrate annual volume and intensity increases exceeding 13% annually. Consultations, hospital visits, and specialist services account for a third of all services provided during the admission and also demonstrate rapid annual rates of growth.