Summary: Cow’s milk allergy is the most common food allergy in infants and young children. Clinical manifestations of this condition are various, but symptoms predominantly affect the skin and gastrointestinal tract. The timing of onset depends on the underlying IgE-mediated or non-IgE-mediated mechanisms. Diagnosis of cow's milk allergy is based on a detailed clinical history, physical examination, skin prick tests, measurement of allergen-specific IgE antibodies to whole milk protein or milk components, a diagnostic elimination diet and, finally, oral food challenge as the most reliable diagnostic tool in food allergy. Guidelines are presented to assure maximum safety and accuracy of the procedure. Basic treatment includes cow's milk allergen avoidance. To prevent a prolonged elimination diet, periodic oral food challenges should be performed to assess tolerance.