Non-celiac gluten sensitivity has recently been recognized by the scientific community as a part of gluten-related disorders, and is defined as a condition with gastrointestinal and/or extra-intestinal symptoms triggered by gluten ingestion in the absence of celiac disease and wheat allergy. Currently, there is no specific serological marker and non-celiac gluten sensitivity remains a diagnosis of exclusion: testing for celiac disease and wheat allergy must be negative, symptoms must improve with a gluten-free diet, and diagnosis must be confirmed by the gluten challenge. In this article, we discuss current knowledge of pathophysiology, clinical and epidemilogical spectrum, diagnosis, and treatment of NCGS.