Food protein-induced enterocolitis syndrome (FPIES) occurs in young infants who present with protracted vomiting and/or diarrhea which generally start 1-4 hours after certain food protein ingestion. Cow's milk and soy protein are most often responsible, but FPIES may be caused by solid foods such as egg white, wheat, rice, nuts, chicken and fish. We report the case of a 12 month-old girl who presented to the Emergency Department with profuse vomiting and diarrhoea having occurred 2 hours after fish ingestion. The patient was dehydrated. Antibiotics and intravenous fluids were administered. Her condition rapidly improved and she was discharged with the diagnosis of gastroenteritis.At the age of 15 months, she was re-admitted to the Emergency Department for the same symptoms, again some 2 hours after fish ingestion. She received the same treatment and rapidly recovered. With the probable diagnosis of fish allergy, the patient was advised to eliminate fish, until further evaluation. At the age of 31 months, a diagnostic oral food challenge was performed and was positive. Skin prick test and serum specific IgE were negative. The diagnosis of FPIES caused by fish protein was established and strict avoidance of fish was recommended.