The purpose of this project is to evaluate the validity of the Index of Medical Underservice (IMU), which was developed for the Department of Health, Education, and Welfare (DHEW) to identify areas which are medically underserved. This problem is being approached through an assessment of the extent to which residents of counties with various lvels of IMU values perceive themselves to be in need of health services. Emphasis is being placed upon primary health care needs considering both physical and mental health. Present and preferred health service utilization patterns will be examined and an attempt will be made to identify factors which facilitate or impede the use of existing and possible future health services. Data are being collected by survey research methods from a stratified statistical probability sample of households in DHEW Region V counties which are at least 50 percent rural as determined by the place of residence of the population. The results of the survey data will be related to data from the Area Resource File for the sampled counties and the counties which are contiguous to them. The analysis will provide an assessment of perceived needs, present and preferred usage patterns, attitudes, and knowledge of individuals regarding health services in their residential area. These results will also provide a set of baseline data for an evaluation of health services delivery programs which may be introduced in the sampled counties subsequent to this study.