A detailed description of the arterial supply of the human cruciate ligaments and surrounding structures is reported as a result of autopsy dissection, contrast medium vascular injections (fine-grain x-rays, and Spalteholz clearing of the specimens), and histologic studies in cadavers of various ages. It has been confirmed that the major supplying vessel is the middle genicular artery, which may show variations in its origin and is frequently double. The fetal and neonatal connections between the branches of this artery and the vascular network of the infrapatellar fat pad, mainly nourished by the terminal branches of the inferior genicular arteries, are usually lost in the adult. A small amount of blood comes to the lower portion of the anterior cruciate ligament from the synovial network supplying the fat pad and the anterior horns of the menisci. Both the femoral and tibial attachments are deprived of vascular penetration from the underlying bone. In spite of the relatively more abundant density of blood vessels around the posterior cruciate ligament, no microangiographic and histological evidence shows that the amount of intrinsic vascularity differs in the two ligaments. Finally, the clinical relevance of the gross and fine vascular anatomy of these articular structures in trauma surgery is considered.