In a study of 42 cases in which open reduction of congenital dislocation of the hip was carried out after conservative treatment had failed, the following observations were made (in a relatively short period of follow-up observation):No one pathological change, as observed at operation, was inordinately associated with failure of closed reduction.By far the highest incidence of successful results of open reduction was obtained in cases in which the operation was done in the second and third year of life. The highest incidence of successful operation, as appraised immediately after the procedure, was in patients more than one year and less than six years of age. Results as determined roentgenographically were in close agreement with results observed clinically.