Skin collagen from fifteen patients with idiopathic adolescent scoliosis, three with congenital scoliosis, and fourteen patients with various degrees of Marfan's syndrome has been examined. 2. The stability of a polymeric collagen fraction, extracted from the skin of these patients, to depolymerization, has been compared with that from thirty-one matched control subjects. 3. The mean polymeric collagen stability was significantly reduced (P less than 0-01) in the group of fifteen patients with idiopathic adolescent scoliosis. The individual reductions in stability were greater in the younger patients and no reduction was found in two patients aged 19 years who had a mature skeleton. 4. The mean stability of polymeric skin collagen from the group of patients with Marfan's syndrome was not significantly abnormal, although there were individual low values. 5. Polymeric collagen of low stability was present in individual patients from each clinical group. Instability of collagen (from whatever cause) at a time of rapid growth may contribute to the high incidence of scoliosis in adolescent girls. In boys, adolescent scoliosis is less common and the maximum growth rate occurs at a time when collagen stability is less reduced.
