Body mass index (BMI) is generally accepted as a useful index of various clinical situations related to obesity. However, there are no reference BMI charts for Saudi children; this paper is an attempt to establish these. A total of 21,638 Saudi schoolchildren between ages six to 16 years (49.6% males) were studied. Curves for BMI, seven percentiles - 5th, 10th, 25th, 50th, 75th, 90th and 95th - were constructed. As a reference material, BMI data for American children were modified into Hegira years. It was found that, in agreement with others, the BMI for the Saudi children studied was age- and gender-dependent. Comparison between Saudi data and international reference showed the expected genetic influence. These results remain to be compared with those from other regions in the Kingdom.