By means of perfusion studies, an analysis was made of the arterial supply to the proximal end of the femur in 150 specimens from autopsied fetuses and children, aged from twenty-six weeks of gestation to fourteen years and eight months old. All died of diseases which did not involve the hip joint. Two anastomotic rings were found: an extracapsular one formed by the medial and lateral femoral circumflex arteries, and a subsynovial intra-articular ring at the articular cartilage-neck junction. The intra-articular rings in males were discontinuous more often than in females. A three-plane analysis of totally-cleared specimens demonstrated that the epiphyseal plate constituted an absolute barrier to blood flow between the epiphysis and metaphysis in all but two of the 124 barium sulphate-perfused specimens examined. A smaller number of ascending cervical arteries crossed the anterior and medial surfaces of the mid-neck in the specimens from three to ten-year-old white children than in those from newborn to two-year-old white and black children. This finding may be important for the etiology of Legg-Perthes disease. No differences with respect to age, sex, or race were found in the arteries of the ligamentum teres.