Along with the improvement of childhood acute leukemia treatment, survival rates have increased. Therefore, the number of long term childhood leukemia survivors has increased progressively over the last decades. So, the assessment of long term health status in this population becomes very important. Many studies have shown an increased risk of life threatening late complications and early mortality. Cardiovascular morbidity and mortality are particularly frequent. Among these late complications, the metabolic syndrome (MS) is an important concern since it is associated with cardiovascular morbidity and mortality. The overall MS prevalence in the French prospective cohort of survivors of childhood acute leukemia was 9.2% and 18.6% in cases of total body irradiation (TBI) during the leukemia treatment. Since the median age at MS evaluation was 21 years, this prevalence was very high. Anyway, the MS pathophysiology in this population is still poorly understood. One of the most recent hypothesis about the MS mechanism is based on the adipose tissue inability to store fatty acids: when adipose tissue cannot expanse further to store excess nutriments then lipids accumulate in other tissues. This ectopic lipids accumulation can cause insulin resistance and MS.