Abstract
We surveyed 4315 2-5 year olds in Iran. Prevalence of obesity (BMI >95th centile, Iranian reference data) was compared with the recent "IOTF" approach. Prevalence was significantly higher than expected, and increased with age, but contradictory trends were obtained from the two approaches. Monitoring of childhood obesity using the BMI in developing countries is indicated, but differences associated with obesity definition should be considered.