PURPOSE A survey was designed to determine accurately the number of full-time equivalent medical oncologists in the United States, to determine how medical oncologists in different work settings divide their professional activities, and to determine whether medical oncology represents a primary care specialty in the minds of practicing oncologists. METHODS A questionnaire was mailed to the 4,239 members of the American Society of Clinical Oncology (ASCO) who identified themselves as medical oncologists or hematologists/oncologists and were current residents of the United States. Follow-up letters, which included a second copy of the questionnaire, were sent to nonresponders. A third mailing, followed by a telephone reminder, was sent to a randomly selected subset of 300 nonresponders to be certain that the initial responders were similar in practice patterns and attitudes to those individuals who had not initially completed the survey. RESULTS A total of 2,540 physicians responded to the first mailing and an additional 187 to the second (64% response rate); a further 196 individuals who were directly contacted completed the survey document. Practitioners appear to see 160 to 200 different patients per month and to devote approximately 72% of their time to patient care activities. Research and teaching comprised only 3% to 4% of professional time for physicians in private practice or Health Maintenance Organization (HMO) settings, in contrast to 16% for those who worked in community hospitals. Medical oncologists frequently serve the role of principal care giver while patients are undergoing cancer treatment. However, medical oncologists devote minimal time providing primary care services to patients and, if required to increase their clinical volume, would prefer to care for more cancer patients than enhance their primary care activities. It is estimated that the present full-time equivalent number (ie, the conglomorate number of oncologists based on 100% professional effort devoted to clinical care) of medical oncologists is approximately 3,600 individuals. This translates into 1.8 medical oncologists per 100,000 adult Americans. CONCLUSION The medical oncology community devotes the majority of its time to providing oncologic patient care and does not provide or appear to wish to provide what the public defines as primary care. The survey estimate of 1.8 medical oncologists per 100,000 adult Americans is in close accord with HMO estimates of the number of desired oncologists. Consequently, the supply appears consistent with the anticipated demand. There does not appear to be an oversupply of medical oncologists in the United States.