Body Mass Index (BMI) charts for boys and girls aged 2-18 years in Iran are presented. The charts are based on a random cluster sample survey of 1702 boys and 1599 girls living in urban Tehran, whose height and weights were measured in the 1990-1992 National Health Survey of the whole country. Charts were constructed using Healy's method as modified by Pan, Goldstein and Yang (1990), and for boys at one point were smoothed manually. The resulting charts are shown to fit the data well and adequately describe raw BMI centiles of urban and rural children elsewhere in Iran. Comparison of these BMI charts with corresponding UK charts showed substantial differences at every age and emphasizes the necessity for the use of locally based BMI norms for assessing body mass of Iranian children.