Cow's milk protein allergy (CMPA) affects 2-7.5% of children; persistence in adulthood is uncommon since a tolerance develops in 51% of cases within 2 years and 80% within 3-4 years. CMPA is an immunological reaction to one or more milk proteins: α-lactalbumin, ß-lactoglobulin, casein, IgE or non-IgE associated, responsible of immediate or late onset symptoms. The suspicion of CMPA is based on detailed family and medical history, skin test, patch test, laboratory test, an elimination diet and food challenge. The general treatment for CMPA is dietary: elimination of cow's milk protein and introduction of extensively hydrolyzed whey or casein formula, amino acid formula, and soy formula. Extensively hydrolyzed whey or casein formula is recommended as first choice for infants in mild or moderate reactions, amino acid formula in severe CMPA and in cases with poor response to extensively hydrolysed whey or casein formula.