The purpose of this study was to explore how the primary care (PC) physician-to-population ratio changed from 1975 to 1985 in counties that were served by an Area Health Education Center (AHEC) in contrast to those counties that were not. The investigation attempted to determine whether any observed changes in this ratio were dependent upon either degree of urbanization or contiguity to a Standard Metropolitan Statistical Area (SMSA). The data source for this study was the Area Resource File. Results indicated that: (a) irrespective of AHEC status, increased degree of urbanization across counties was associated with relatively more PC physicians in both 1975 and 1985; (b) PC physician-to-population ratios increased from 1975 to 1985 for all American Medical Association (AMA) county code categories, regardless of AHEC versus non-AHEC designation; (c) AHEC counties demonstrated greater (or equivalent) absolute improvement for all AMA county code categories except for several categories which represented more urbanized counties; (d) for the least urbanized counties in the AMA code, the percentage improvement in PC physician-to-population ratios for AHEC counties ranged from 3 to 5 percent higher than corresponding percentage improvement in ratios for non-AHEC counties; and (e) AHEC counties showed greater absolute and percentage improvement in PC physician-to-population ratios than did non-AHEC counties for counties not contiguous to SMSAs.