Cartilage-hair hypoplasia (CHH) is a rare autosomal recessive disorder characterized by metaphyseal chondrodysplasia with severe growth retardation and impaired immunity. We studied the effects of growth hormone treatment on growth parameters and the immune system in four children with CHH. The effects of growth hormone on growth parameters are the most prominent in patients with the mildest growth retardation. However, the effects are temporary and last only for 1 year. There is no gain in final height. Serum immunoglobulins did not change during growth hormone treatment. We conclude that growth hormone treatment is not beneficial in children with CHH.