Thirty-six proximal femoral heads of cadaveric specimens between 0 and 33 months old were the object of a study for the anatomic and radiologic location of the center of the femoral head. The authors verified the sphericity and determined their geometric center. The center is found on the physis of the longitudinal growth of the neck. X-rays show a correlation with the anatomic dissection of the location of the center of the femoral head on the physis at a distance from the metaphysis of 3.7 mm in children under 3 months old, 2.3 mm in 3- to 6-month-old children, 1.4 mm in children 7 to 18 months old, and 0.2 mm in children 19 to 33 months old. The way in which the center must be located on a pelvis x-ray is described. This center is useful in the measurement of Wiberg's angle in small children.