Six hundred fifteen children (310 with diabetes, 106 nondiabetic siblings, and 199 nonsibling controls) were examined for the presence of joint contractures. Forty children had contractures: 8.4 per cent of those with diabetes and 4.6 per cent of those without diabetes. Contractures were present, however, in 9.4 per cent of nondiabetic siblings, and only 2 per cent of nonsibling controls, suggesting a familial tendency to joint contractures. The older the patient, the more likely he was to have contractures. There was no correlation with sex, race, or age at onset of the disease.