Insulin-like growth factors (IGFs), initially known as somatomedins, and their specific, high-affinity binding proteins (IGFBPs) are synthesized in most tissues, but principally in the liver. The interest of measuring their circulating levels, which reflect liver production, is to obtain indications as to their endocrine function and regulation. IGF-I plays a pivotal role in post-natal growth. Its half-life is significantly increased by its association with IGFBPs and its serum levels reflect somatotropic status, unlike growth hormone (GH) which has a much shorter half-life and whose secretion comes in pulses. Since investigation of growth retardation must include the most finely tuned appreciation possible of somatotropic secretion, assays of IFG-I and electrophoretic analysis of IGFBP profile can be useful tools, both diagnostically and therapeutically, and can help in determining the need or otherwise for GH treatment, especially in view of the growing demand for such therapy.