Because there is limited information concerning the vascular pattern and the role of vessels in patients with proximal femoral focal deficiency, the vascular supply of the lower extremities was studied systematically with use of computed tomographic angiography in order to identify vascular changes, relate any vascular changes to the classification of the deficiency, and establish that there are no major changes in the topographical anatomy of the vessels. Standardized computed tomographic techniques were used in twenty-one patients (thirteen boys and eight girls who ranged from one to nineteen years old) with proximal femoral focal deficiency types I through IV and VII, VIII, and IX, according to the Pappas classification. A common anatomical vascular pattern, in which the hypoplastic extremity was supplied through the femoral artery, was detected in nineteen patients. In patients with Pappas type-I through IV disease, the external iliac, femoral, and deep femoral arteries were substantially reduced in length and diameter and the deep femoral artery arose more proximally in comparison with that in the contralateral extremity; however, in the patients with Pappas type-VII, VIII, or IX disease, the diameters of the arteries and the origin of the deep femoral artery were similar to those of the contralateral extremity. In two patients with Pappas type-III disease, atypical anatomy of the vessels was found. The anterior part of the thigh and the pseudarthrosis were supplied through the femoral artery (the external iliac artery) as a terminal branch, while the remainder of the extremity was supplied from the internal iliac artery, which entered the thigh posterior to the hip as the inferior gluteal artery and continued as the artery to the sciatic nerve to the popliteal artery. No substantial anastomoses were found between the femoral and the posterior arteries in these vascular patterns. Computed tomographic-angiographic reconstruction can be used to depict the spatial configuration of the pseudarthrosis and the vascular pattern of the extremity in patients with proximal femoral focal deficiency. We found distinct vascular changes in the majority of the involved thighs, but there were no typical changes related to the Pappas classification. Because we found atypical vascular patterns in two patients, evaluation of the vessels with use of various diagnostic methods is recommended in patients with severe types of proximal femoral focal deficiency.