The purpose of this study was to estimate usage of vitamin and mineral supplements as over-the-counter (VM-OTC) drugs as well as examine factors associated with VM-OTC usage in Korean adolescents. A total of 1,407 adolescents attending middle or high school in all parts of country were included in the analysis. Prevalence of VM-OTC usage was 56.1%, and it was higher as monthly income, father’s education level, and socioeconomic status of family increased (p<0.001). VMOTC intake was higher in middle school students than in high school students as well as in rural areas or small & mediumsized city residents than big city residents (p<0.01). Subjects mainly received information on VM-OTC mainly from ‘family and relatives’ (46.6%), whereas only 20.3% received information from experts. Subjects took VM-OTC ‘when they are healthy’ (49.1%), ‘when they feel sick’ (17.7%), ‘when they are on a diet’ (17.3%), and ‘when they are stressful’ (15.9%). The effectiveness of taking VM-OTC were mainly ‘fatigue recovery’ (35.0%), ‘health improvement’ (30.6%), and ‘nutritional status improvement’ (13.2%). The most frequently used VM-OTC was vitamin C (49.1%), multi-vitamins (18.6%), multi vitamins & minerals (13.2%), and calcium (9.2%). Among VM-OTC users, only 21.9% replied that they usually check the nutrition facts when they buy products, 62.4% follow the recommended dosage, and 9.7% fully understand the nutrition labels of the products. According to logistic regression analysis, the most influential factor affecting VM-OTC use was parents’ and siblings’ VM-OTC consumption (p<0.001). In addition, school type (middle or high school) (p<0.01), residence (p<0.05), self-concerns about health (p<0.05), father’s education level (p<0.05), and socioeconomic status of family (p<0.05) all influenced VM-OTC use. These results show that VM-OTC use is widespread among adolescents, few users actually check and fully understand the nutrition labels when they purchase VM-OTC, and they are highly dependent on unprofessional advice and information. Therefore, it is necessary to educate adolescents to help them select proper VM-OTC and read nutrition labels.