This study was conducted to determine how the regional health insurance program, put into effect nation-wide, might affect paterns and extent of medical care utilization in rural areas. The study employed a "one-group, before-after design" and the data were collected from two sampling surveys conducted in Kangwha County, based on "multi-stage, stratified cluster sampling. "Changes in ambulatory care utilization, as measured in terms of the number of visits per 100 persons during the two-week survey period, varied with the type of facility. Out-of-pocket expenses for medical care connected with all forms of facilities were found to have decreased during the time interval due to insurance coverage. Before insurance, when a person sought medical help at a drugstore, it was more often because it was conveniently close and he or she was old and believed himself or herself to not be seriously ill; when a person sought medical help at a clinic or hospital, it was because he or she believed himself or herself to be seriously ill(i.e. only morbidity condition was a significant factor). After insuranc, when a person sought help at a drugstore, it was mainly because he or she was old and the drugstore was conveniently located. when a person sought help at a clinic or hospital, it was because he or she believed himself or herself to be seriously ill and, in addition, because the facility was conveniently located (i.e. geographical accessibility became an added factor of significance). Furthermore, knowledge of benefit coverage increased as residents gained more experience with the program during the interval between surveys.