The proximal femoral epiphysis from the right hip of twenty-five mongrel puppies was surgically devascularized on two occasions separated by a four-week interval. Before death the bone was labeled with substances fluorescing in ultraviolet light and the animals were then killed at varying intervals after the second infarct. The specimens were studied by naked-eye inspection, roentgenography, histology and autoradiography. The resulting changes in the epiphysis are described. Apical lytic lesions similar to those seen in Perthes disease in man were observed in certain specimens and the genesis of these lesions is discussed. It is speculated that Perthes disease in man may be due to more than one episode of infarction.