The purpose of this study was to examine whether smoking frequency and cigarette consumption were related with obesity in Korean adolescents. A total of 72,399 adolescents from 1st grade middle-school to 3rd grade high-school participated in the 5th Korea Youth Risk Behavior Web-based Survey (KYRBWS) project in 2009. The relationship between the body mass index (BMI), smoking frequency, and cigarette consumption was assessed using multivariate logistic regression analysis after adjusting for covariate variables like age, frequency of alcohol consumption and severe alcohol intoxication, amount of alcohol consumed, parents' education level, economic status, sedentary activities during the week, mental stress, sleep duration, frequency of vigorous and moderate physical activities, and muscular strength exercises during the week. We concluded that both smoking frequency and cigarette consumption had positive effects with regard to weight loss in adolescents. However, because smoking has negative side effects on general health, including an increase in abdominal fat and morbidity rates of obesity-related diseases, we recommend that adolescents should not smoke (Tab. 3, Ref. 26).