Implementation of gluten-free diet in a patient with symptoms from alimentary tract should be carefully considered in aspect of clinical interview, physical examination and medical tests (serological markers of celiac disease, small bowel biopsy). The aim of this study was to point out consequences of too hasty application of a gluten-free diet and necessity of proper diagnostics in cases where symptoms suggest food hypersensitivity. In this article authors present 17-month-old girl who was ordered a gluten-free diet after 7 days symptoms of acute diarrhoea, without fulfilling tests which could either exclude or confirm diseases like food allergy or celiac disease.