The purpose of this study was to compare sex differences in Body Mass Index, subjective perception of body weight, body shape satisfaction, and self-esteem in Korean adolescent boys and girls. Subjects were 109 boys (M age = 16.1 yr., SD=.6) and 131 girls (M age=16.0 yr., SD=.5), recruited from two high schools in Korea. There were differences in Body Mass Index, perception of body weight, body shape satisfaction, and self-esteem by group. More girls (31%) than boys (16%) evaluated themselves as overweight, while higher proportions of boys (6.4%) than girls (1.5%) were actually overweight. A higher proportion of girls responded that they were dissatisfied with their body shape (61% vs 28%). Self-esteem mean score was significantly higher for the boys than the girls. There was a significant relationship between actual Body Mass Index and perception of body weight. There was a significant negative relation between Body Mass Index and rated self-esteem for girls.