Objective.We examined associations between density of and proximity to fast food outlets and body weight in a sample of children (137 aged 8-9 years and 243 aged 13-15 years) and their parents (322 fathers and 362 mothers). Methods. Children's measured and parents' self-reported heights and weights were used to calculate body mass index (BMI). Locations of major fast food outlets were geocoded. Bivariate linear regression analyses examined associations between the presence of any fast food outlet within a 2 km buffer around participants' homes, fast food outlet density within the 2 km buffer, and distance to the nearest outlet and BMI. Each independent variable was also entered into separate bivariate logistic regression analyses to predict the odds of being overweight or obese. Results. Among older children, those with at least one outlet within 2 km had lower BMI z-scores. The further that fathers lived from an outlet, the higher their BMI. Among 13-15-year-old girls and their fathers, the likelihood of overweight/obesity was reduced by 80% and 50%, respectively, if they had at least one fast food outlet within 2 km of their home. Among older girls, the likelihood of being overweight/obese was reduced by 14% with each additional outlet within 2 km. Fathers' odds of being overweight/obese increased by 13% for each additional kilometre to the nearest outlet. Conclusions. While consumption of fast food has been shown to be associated with obesity, this study provides little support for the concept that exposure to fast food outlets in the local neighbourhood increases risk of obesity.