BACKGROUND: The prevalence of overweight and obesity in children is steadily increasing in many countries. Dental caries and obesity are both multifactorial diseases and are associated with dietary habits. OBJECTIVE: The purpose of this study was to investigate the relationship between body weight status in adolescents and snacking habits in early childhood to approximal caries prevalence at 15 years of age. METHODS: This study is part of a series of surveys of oral health in children followed from the ages of 1 year to 15 years. Body adiposity status was estimated at 13.5-16.4 years using the International Obesity Task Force cut-off values [age-specific body mass index (isoBMI)]. Information about snacking habits in early childhood was collected from interviews conducted at 1 year and 3 years. Approximal caries information was obtained from bitewing radiographs at 15 years. Data related to isoBMI and approximal caries were available in 402 teenagers. RESULT: Adolescents with isoBMI > or = 25 (n = 64) had an approximal caries prevalence that was a mean of 1.6 times higher than those with isoBMI