Cow's milk allergy is a disease of infancy and usually appears in the first few months of life. The evaluation of infants for possible cow's milk allergy is one of the more common problems encountered by pediatricians. Unfortunately, both over and under diagnosis is frequently seen. In this review the pathophysiology, the clinical manifestations, the diagnosis and management of infants with cow's milk allergy as well as the prevention of the condition in predisposed infants are discussed.