As with Legg-Perthes disease, the revascularization of an undisplaced fragmeat in osteochondritis dissecans of the knee in children appears to proceed with reasonable rapidity in certain cases, providing the joint is protected from weight-bearing. The roentgenographic findings in the two cases herein reported suggest that, in children. treatment in which weight-bearing is not allowed should be adopted for a period of at least six months,—surgery being reserved only for those cases in which clinical and roentgenographic improvement cannot be demonstrated or in which displacement occurs.