Collagen metabolism was studied in fibroblasts grown from a skin biopsy specimen of a patient who presented the striking clinical features of Ehlers-Danlos syndrome and, in particular, hyperextensibility of the skin, hypermobility of the joints, and kyphoscoliosis. A reduction in lysine hydroxylation, characteristic of Ehlers-Danlos Type VI, was observed after labeling of the collagen with 14C-proline and 3H-lysine. Other modifications in the collagen metabolism of fibroblast cultures were noted, including an increase in collagen and total protein synthesis, and an increase in both the Type I and Type III collagen. The percentage of Type III collagen was, however, lower than in the control fibroblasts. The results point out the complexity of collagen disturbances in Ehlers-Danlos Type VI.