A review of the English literature on Blount disease (osteochondrosis deformans tibiae; tibia vara) revealed that two forms of the disease, infantile and adolescent, are recognized. The cause of Blount disease is probably multifactorial. Most recent evidence on the pathogenesis implicates mechanical factors. The diagnosis can be difficult in very young children and must be based on history, physical examination, and radiographic findings. A proximal tibial metaphyseal-diaphyseal angle of greater than 11 degrees should be observed carefully for the development of Blount disease. Both nonoperative and operative treatment has been used successfully.