A Health Interview Survey at Chuncheon city was conducted to assess level of illness by stratified random sampling method. Sample size was 6,007 and the prevalence of illness in period of 15 days was studied. 1) Prevalence rate of illness among Chuncheon citizen was 20.8 percent, and that of acute condition was 10.8 percent and chronic condition, 10.0 percent. 2) There was significant difference in prevalence rate by sex, especially the prevalence rate of chronic illness. 3) High positive correlation was noted between aging and prevalence rate of chronic illness. But negative correlation was noted in case of acute illness. 4) Multiple regression analysis on morbid state by socioeconomic variables was not seen to be appropriate for this survey, especially the analysis of acute illness. 5) Estimation of anual prevalence rate could not be possible because of seasonal variation of disease prevalence.