An emerging problem in clinical practice is how to manage the growing number of patients who experience symptoms related to the ingestion of gluten-containing foods gluten and in whom celiac disease has been ruled out. These patients most frequently report gastrointestinal symptoms such as diarrhea, abdominal discomfort or pain, bloating, flatulence, but also extraintestinal symptoms, including headache, lethargy, attention-deficit/hyperactivity disorder, ataxia, or recurrent oral ulceration. This heterogeneous syndrome, which has been reported to improve or even disappear after gluten withdrawal and to relapse after gluten challenge, is called non-celiac gluten sensitivity.1 The concept of nonceliac gluten sensitivity is not completely new. Besides several sporadic single cases reported, more than 30 years ago an oral, double-blind, placebo-controlled, cross-over gluten challenge trial showed that six out of eight adult non-celiac patients, who suffered from intestinal symptoms caused by the ingestion of gluten-containing food, were affected by gluten-sensitive diarrhea. Over the last few years, an intense debate about the existence and the prevalence of nonceliac gluten sensitivity has emerged, as shown by the considerable increase in internet forums of discussion on this topic and in availability of gluten-free food. A definition of nonceliac gluten sensitivity based on definitive scientific evidence does not still exist, and the clinical trials conducted so far in order to fill this knowledge gap are burdened by a number of biases. In a cross-over trial of subjects with suspected NCGS, the severity of overall (intestinal plus extraintestinal) symptoms increased significantly during 1 week of intake of small amounts of gluten (daily 4.375 grams), compared with placebo. Among the 59 participants in this trial, the Investigatotors identified only three true gluten-sensitive patients, defined as having a delta overall score -calculated by subtracting the weekly overall score under placebo from that under gluten- higher than the mean delta overall score plus 2 standard deviations. However, these results should be cautiously interpreted due to the lack of a control group of non-gluten-sensitive subjects.