This article reviews the epidemiology of cancers arising in the distal oesophagus and proximal stomach, sometimes collectively termed oesophago-gastric junctional adenocarcinomas. The several complexities involved in defining this group of cancers are considered and the reported increasing trends in incidence are reviewed, together with the descriptive epidemiology. The rates of these cancers are increasing, but not as dramatically as sometimes reported. They are also more common in white males than in other ethnic groups or in females. Although several aetiological risk factors have been reported, the two most consistent are an elevated body mass index (obesity) and a history of gastro-oesophageal reflux disease. Reflux is also associated with Barrett's oesophagus, an important and increasingly diagnosed premalignant lesion. The rate of progression from Barrett's oesophagus to cancer is controversial, as is the cost–benefit balance of routine endoscopic surveillance of such patients. The development of molecular biomarkers to identify Barrett's oesophagus patients with high rates of malignant transformation would represent a significant advance.