The coming decade will bring dramatic changes in the composition of the American population. Changes in immigration laws, illegal and legal immigration into this country, and the aging of the "baby boomers" will all result in profound changes in the demographics of this country. These demographic changes will necessitate alterations in all aspects of the health care system. This article focuses on the projected changes that will occur in relation to the elderly, Hispanics, Asian Americans, and the economically disadvantaged, and on the related implications for health care professionals. The cancer incidence and mortality rates for each discussed minority group differ from the rates presently reported for white Americans. Thus, health professionals will have to be aware of the differences among these groups and tailor their primary and secondary prevention efforts accordingly. The future task for all health care providers serving minorities and the elderly will be to familiarize themselves with the special health problems of the population with whom they work and with the ethnocultural barriers that deter proper use and delivery of health services.