In Muscatine, Iowa, a medically underserved rural area, a cohort study of health care utilization was made before and after a significant increase in medical manpower. There was a slight increase, rather than a decrease, in the use of chiropractic services associated with the growth in the physician manpower pool. The level of access to physician services was not a significant predictor of chiropractice utilization. (Am J Public Health 70: 415-417, 1980.) ed opportunities of chiropractors make rural locations relatively attractive to them."5 That is, chiropractors could have a "filling" effect by offering their services in medically underserved rural areas, with rural residents using chiropractors to fill primary care needs.We recently had the opportunity to examine whether chiropractic utilization serves as a substitute for orthodox medical services employing two surveys of medical care utilization in a rural community, before and after a dramatic increase in the number of primary care physicians. Methods IntroductionThe place of chiropractic in the delivery of personal health services is not well defined. To many in the medical community it is synonymous with quackery, but to over seven-and-a-half million Americans, chiropractors are a source of health care.' Rural residents, whose health care supply is often deficient, are among the highest users of chiropractors,1 a fact not totally explained by the higher average age and lower family incomes of rural consumers. In keeping with the reduced medical service supply, rural residents average fewer physician visits per year than their urban counterparts. [1][2][3][4] Hassinger, et al, hypothesized that the "erosion of medical and osteopathic physicians (from rural areas) results in need for personal health services, and the more limit-

From January 1 to April 30, 1986, all Intravenous (IV) drug users and male homosexuals are the two major groups known to be at risk for AIDS (acquired