CONTEXT: Recent data indicate a marked increase in the prevalence of obesity among school-aged children. Thus, efficacious programmes that prevent overweight development in children are urgently needed. OBJECTIVE: To evaluate the impact of repeatedly given, individualised dietary and lifestyle counselling on the prevalence of overweight during the first 10 years of life. DESIGN AND PARTICIPANTS: This study was a part of the Special Turku Coronary Risk Factor Intervention Project for Children (STRIP), which is a prospective, randomised trial aimed at reducing the exposure of the intervention children to the known risk factors of atherosclerosis. At the child’s age of 7 months, 1062 children were assigned to an intervention group (n=540) or to a control group (n=522). The intervention children received individualised counselling focused on healthy diet and physical activity biannually. Height and weight of the children were measured at least once a year. MAIN OUTCOME MEASURE: Prevalence of overweight and obesity among the intervention and control children by sex and age. Children were classified as overweight or obese if their weight for height was >20% or > or =40% above the mean weight for height of healthy Finnish children, respectively. RESULTS: After the age of 2 years, there were continuously fewer overweight girls in the intervention group than in the control group. At the age of 10 years, 10.2% of the intervention girls and 18.8% of the control girls were overweight (P=0.0439), whereas 11.6% of the intervention boys and 12.1% of the control boys were overweight (P approximately 1.00). Only three children in the intervention group were obese at some age point, whereas 14 control children were classified as obese at some age point. CONCLUSION: Individualised dietary and lifestyle counselling given twice a year since infancy decreases prevalence of overweight in school-aged girls even without any primary energy restrictions.