The National Study of Internal Medicine Manpower was undertaken to collect data on the supply of newly trained internists. The questionnaire data returned by 98% of the 418 internal medicine residency training program directors showed that there were more than 15,000 residents in training in internal medicine in 1976-1977. Twenty-five percent of the first-year positions were held by physicians destined for specialties other than internal medicine. Over a third of each medical school graduating class opts for a full year of internal medicine for their first residency year; an additional third of all medical school graduates rotate for a variable number of months on internal medicine teaching services. More than half of the practicing internists participate in the training of residents. Hospital revenue (for example, Medicare and third-party payers) provides the bulk of financial support for residents and teaching staff. Local, state, and federal governments, by direct appropriation, provide 25% of residents' stipends and teaching staff salaries.