Purpose : The aim of this study was to investigate patterns of medical use among juveniles and adolescents, including for chronic disease, in Korea. The study sought to do the following: (a) investigate the extent to which chronic diseases account for medical expenditures, (b) investigate and the socio-demographic characteristics associated with medical use, and (c) identify the differences in medical use between juveniles and adolescents. Methods : We used data from the 2015 Korean Health Panel and selected 12 variables. The socio-demographic characteristics investigated included, growth period (juvenile, adolescents), gender, family income, national basic livelihood act status, disability registration, and degree of disability. There were five medical factors that were considered: emergency room use, hospitalization use, hospital outpatient use, chronic disease, and medical expenditure. Data were analyzed using stepwise multiple and logistic regression. Results : The prevalence of chronic disability in juveniles and adolescents was 31.1 % and 1 %, respectively. The factors affecting medical expenditures included hospitalization use, hospital outpatient use, family income, disability, gender, chronic disease, and emergency room use ($R^2=.160$, p<.05). For national basic livelihood act recipients, the probability of having chronic disease was about 1.6 times higher (OR=1.597, 95 % CI=1.092-2.335, p=.016), compared with non-national basic livelihood act recipients. People with disabilities were 6.6 times more likely than those without disabilities to suffer from chronic disease (OR =6.571, 95 % CI=2.776-15.556, p<.001). Hospital outpatient user was 2.3 times higher than non-user (OR=2.260, 95 % CI=1.702-3.001, p<.001). Juveniles had a 1.7 times and 6.2 times higher likelihood of emergency rooms user (OR=1.654, 95 % CI=1.270-2.155, p<.001), and hospital outpatient user than adolescents (OR=6.208, 95 % CI=4.443-8.676, p<.001). Conclusion : The findings of this study suggest that health care services for juveniles is needed to manage chronic diseases that have an effect on medical expenditures.