Lower extremity bowing is a normal physiologic process that commonly occurs in walking children under the age of 2 years. After this age, any significant amount of residual bowing is abnormal and may be due to infections, traumatic physeal injuries, genetic predisposition, metabolic factors, or a combination of these. Of the pathologic conditions, infantile Blount's disease is the most common and is predominantly found in obese children with an early onset of walking. Because of its frequency in occurrence and general tendency for spontaneous resolution, physiologic genu varum must be clearly distinguished from other pathologic processes that result in bowleggedness. Treatment of the latter cases may consist of early bracing or surgery.