This report provides Body Mass Index (weight/height2) values for the French population from birth to the age of 87 years. BMI curves increase during the first year, decrease until the age of 6, increase again up to 65 years and decrease thereafter. These variations reflect the total changes of fat body mass during life. The 50th centile values of Wt/Ht2 at the ages of 20, 40, 60, 80 years are 21.5, 24.6, 25.4, 24.4 kg/m2 for men and 20.6, 22.6, 24.1, 23.4 kg/m2 for women. The values for the 3rd, 50th and 97th centiles in the middle years are approximately 18, 24 and 32 kg/m2. Graphs for these and four other percentiles are plotted against age, and two other graphs summarising the variation and skewness of the Wt/Ht2 distribution are provided to calculate exact percentiles and Z-scores for individuals.