The prevalence of cow's milk allergy is stable, between 2% and 5%. Clinical symptoms are numerous. Gastroesophageal reflux and persistent constipation have been recently described. The main point is the increasing prevalence of multiple food allergens. Double blind placebo controlled milk challenges are mandatory for the diagnosis, sometimes eight days long. The proof of the IgE-dependent sensitization, or of lymphocyte activation is not always brought. ECP, methylhistamine and tryptase dosages coupled to challenges are not clearly informative tests. The eviction of dairy products is completed by substitution by casein hydrolysates or pork collagen or soy hydrolysates, or by formula made from amino acids. Tolerance protocols are not standardized, however valuable. Review documented by 98 references.