We describe 2 cases of food protein-induced enterocolitis syndrome (FPIES) caused by cow's milk (CM) passed through breast milk. The onset in both cases was characterized by chronic symptoms (regurgitation, colic, diarrhea, failure to thrive); in one patient, two acute episodes due to the direct consumption of CM formula by the infant were also reported. The diagnosis of FPIES through breast milk can be easily overlooked, especially in milder cases. We also discuss some important issues concerning the general management of the disease. In conclusion, (1) the diagnosis of chronic FPIES should be taken into account even in exclusively breast-fed infants who present suggestive symptoms such as persistent regurgitation, small amounts of vomiting, lethargy, failure to thrive, dehydration, diarrhea (sometimes bloody) and abdominal distention. A 2-week maternal elimination diet should be considered even in apparently mild cases. (2) CM seems to be the most frequently reported culprit food. (3) In those cases in which acute FPIES is elicited by the direct consumption of the culprit food in breast-fed infants, maternal diet may be unrestricted.