AIMS: To study if there is a change in paediatric overweight/obesity prevalence from 1982 to 2002 in a population with a high proportion of post-graduate education. DESIGN: Two samples of children in Uppsala County, Sweden, were compared: children who were 4, 10 and 16 year old in 1982; or 4, 10 and 16 year old in 2002. Mean BMI (in the lowest 10%, middle 50% and highest 10%) and ISO-BMI ('age adjusted BMI') cut-off values were calculated in each age and gender group. RESULTS: Using the mean BMI or ISO-BMI cut-off values, the BMI-distribution shifted from 1982 to 2002. More 4- and 10-year-old girls and boys were overweight/obese, although this shift was larger in girls. No shift was seen in the 16-year-olds, only the middle 50% group in the 16-year-old girls had a slight increase of their mean BMI. In the 2002 4-year-old, and both 10-year-old samples, a higher proportion of the girls were overweight/obese compared to the boys, but no difference was seen in the 16-year-old sample. CONCLUSION: Young children, especially girls, have become much more overweight/obese during the past 20 years, despite a high proportion of post-graduate education in the population. The lack of major change in 16-year-olds may suggest a rather recent change in the children's environment/lifestyle.