The avoidance of wheat- and gluten-containing products is a worldwide phenomenon. While coeliac disease is well-established, much remains unknown about whether gluten can be a trigger of gastrointestinal and/or extra-intestinal symptoms in patients without coeliac disease. In this article, we discuss the latest scientific evidence and our current understanding for the possible mechanisms of this largely ambiguous group, termed 'non-coeliac gluten sensitive' (NCGS). We can conclude that NCGS should be regarded as an independent disease outside of coeliac disease and wheat allergy, and that the number of patients affected is likely to be limited. Many questions remain unanswered and it needs to be verified whether the elimination of dietary gluten alone is sufficient for the control of symptoms, and to understand the overlap with other components of wheat.