Allergies are a real emerging public health problem worldwide. Their frequency has increased considerably in recent years. Food allergies start in early childhood and most of them disappear with time, their increasing importance has justified regularly updated studies. CMPA is the first food allergy to appear in childhood and the most frequent in infants during the first year of life. Being a very old allergy in its description, it is the best known in pediatrics. It is a reaction of the immune system against one or more cow's milk proteins (all potentially allergenic). With the progress of pediatric allergology and the progression of the reflections on allergological and nutritional pathologies in children, in particular cow's milk protein allergy, our practice has been enriched in recent years. A better knowledge of the immunopathological bases and the use of diagnostic means have made the diagnosis easier.