A unique patient with type VIII Ehlers-Danlos syndrome and cutaneous vasculitis, resorptive osteolysis, and cardiac valvular disease is described. Collagen analyses identified morphologic and physical abnormalities of type I collagen. The patient's T lymphocytes could be propagated in vitro with type I collagen and produced a 60-kd lymphokine that bound this protein. Cellular autoimmunity to type I collagen may be responsible for this patient's intractable clinical condition.