During the last century, gastro-oesophageal reflux disease (GERD) has become increasingly observed in Western countries. The disorder is chronic and relapsing with a clinically significant impairment in quality of life. Symptoms of GERD are very common in the general population. However, reported symptoms under-represent the true prevalence of the disease, because these do not equate with mucosal damage, and this might lead to a bias in epidemiologic surveys. Several studies have been conducted in endoscopic centres, but these were able to focus on only some consequences of GERD (oesophagitis or Barrett's oesophagus) and not on nonerosive reflux disease (NERD). The latter is a clinical condition characterised by symptoms of reflux and intraesophageal gastric content reflux in the absence of visible endoscopic oesophageal mucosal injury. Moreover, the diffuse use of acid suppressing drugs in the population is able to mask some manifestations of GERD. Other studies have been conducted in the form of questionnaires investigating the presence and the frequency of symptoms typical of GERD. These estimates have taken into consideration and assumed that heartburn is an indicator of the disease. Taking into account the many faces of GERD, and its wide spectrum of manifestations, including atypical symptoms, this could represent a serious limitation. This brief review article fosters understanding of this issue by focusing on the epidemiology of GERD.