The purpose of this study is to compare the nutrition knowledge, dietary behavior and food frequency according to the gender and weight control attempt among middle school students in Seoul and Gyunggi-do, Korea. The subjects were divided into three groups, one with experience in attempting to lose their weight, one with experience in attempting to gain their weight and one with no experience in attempting to control their weight. Nutrition knowledge level of girls was higher than that of boys (p<0.01), but there were no significant difference according to weight control attempt. As for the scores of dietary behavior, there were no significant differences by gender but according to weight control attempt, the scores of dietary behavior of the weight loss attempt group were higher than those of the other attempt groups (p<0.01). In the food intake frequency, there were significant differences according to weight control attempt (p<0.05, p<0.01).