Apolipoprotein B (apo B) is the major component of LDL, VLDL and chylomicrons. Variations of lipid concentrations in obese people result from obesity, nutritional and genetic factors. Many genetic polymorphisms of the apo B have been described, associated with variation of lipid concentrations. The aim of the present study was to assess the effect of VNTR3' polymorphism of the apoB gene on lipid and lipoprotein concentrations in overweight subjects. 234 unrelated outpatients (160 women and 74 men, aged 39.3 y 10.5; BMI: 32.8 kg/m2 4.7) were recruited. Using the polymerase chain reaction followed by electrophoresis in polyacrylamide gels, 15 different alleles have been identified. Among them four have been observed less than 5 times in our study. Alleles with 21, 25, 35 and 42 repeats have been observed once. The most frequent is VNTR36 allele (38%), followed by alleles 34, 30, 48, and 46 repeats whose frequencies are 20, 9, 8, and 7% respectively. The possible association between alleles of the VNTR3' of the apoB and anthroprometric and lipid variables was examined. Subjects with 50 repeat allele had significantly higher BMI, and subjects with 32 repeat allele had significantly higher HDL-C and ApoAI levels. Our study confirms in the obese subjects, results published in the general litterature, and shows that the apoB has an important role in the metabolism of plasma lipids and most particulary its gene variants.