Objective: To investigate parents’ misperception of their active children’s size. Subjects: One hundred and forty male or female parents and their children from a youth soccer league participated. Actual Child Body Mass Index (BMI) percentiles and BMI categories were compared to the results of a Body Size Estimation Task and lifestyles questionnaire results. Results: Parents underestimated the body size of their children and placed them in a lower BMI category than the children actually belonged in. As was the case in other studies children in the unhealthy or at risk to become overweight category where seen as a healthy weight. Unlike other studies, many healthy weight children were seen as underweight. Conclusions: An explanation of body size misperception and underestimation of body size may be “change blindness”. The growing prevalence of obesity in children may be better addressed by focusing on the parents’ apparent lack of concern about excess childhood weight and the parents’ identification of excess childhood weight as “just normal” rather than seeing excess weight as a potential problem.