In order to investigate supplement use in middle-aged and elderly outpatients suffering from age-related diseases over the last year, a cross-sectional survey was conducted from July to December 2001. The subjects were 1702 (male 731, female 971) age-related disease outpatients over age 50. Data was collected using a standardized questionnaire and in-person interviews. The prevalence of supplement use and the different categories of supplements taken by the subjects were examined using SPSS statistical package. Supplements were used by 48.9% of the subjects. The mean number of kinds of dietary supplements taken by subjects was 1.7. Chinese medicine was the most commonly used supplements in both the male and female subjects. Among the reasons for using supplements, health promotion ranked as the most common. Most of the supplement users, however, did not know or only knew roughly about the health claims of their supplements. Subjects reported the information source on supplements as family, friends or relatives followed by doctors or pharmacists. These results may provide basic information for proper supplement use among Korean middle-aged and elderly outpatients with age-related diseases.