Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE mediated hypersensitivity disorder, which is associated with mainly gastrointestinal symptoms and has a delayed onset. The vomiting and/or diarrheal symptoms of FPIES typically begin in the first month of life in association with a failure to thrive, metabolic acidosis, and shock. Therefore, the differential diagnosis of FPIES and neonatal or infantile sepsis-like illnesses or gastroenteritis is difficult. The early recognition of indexes of suspicion for FPIES may help in the diagnosis and treatment of this disorder. The diagnosis of FPIES is generally made through clinical practice and food-specific IgE test findings are typically negative in this condition. Therefore, oral cow's milk challenge (OCC) remains the valid diagnostic standard for FPIES. An investigation of positive OCC outcomes helps to find out a diagnostic algorithm of criteria of a positive challenge in FPIES. Moreover, it has not been clearly determined in infantile FPIES when 1st follow up-oral food challenge (FU-OFC) should be performed, with what kind of food protein (e.g., cow's milk, soy), and how much protein should be administered. Hence, to prevent the risk of inappropriate FU-OFC or accidental exposure and achieve appropriate dietary management, it is necessary to identify tolerance rates to major foods under the careful follow up of infantile FPIES patients. On the other hand, small intestinal enteropathy with villous atrophy is observed in FPIES and this enteropathy seems to be in part induced by both of epithelial apoptosis and intercellular junctional complex breakdown. The purpose of this report is to introduce an update on diagnostic and therapeutic approaches in FPIES and suggest the possible histopathological evidences in this disorder.