 According to recent data, about 400 patients would be followed in the Belgian hospitals, and about 1 in 1500 newborns in Belgium would be a major carrier of hemoglobinopathies. The most expressive and most frequent complication of the disease is vaso-occlusive crisis, dominated by a painful syndrome. In addition to vaso-occlusive crises, many more chronic biological disturbances are observed in sickle cell patients. Their contribution to the course of the disease is becoming increasingly stressing. Among them are intravascular hemolysis, hyper-adhesion of blood cells to vascular endothelium, inflammation, oxidative stress, vasculopathy and bleeding disorders. 