Gastro-oesophageal reflux disease (GERD) is a disorder in which reflux of stomach contents causes troublesome symptoms and/or complications and which affects health-related quality of life. It is one of the commonest disorders and appears to be increasing in incidence. The mechanisms leading to reflux are complex and multifactorial. The lower oesophageal sphincter (LES) is an important part of the gastro-oesophageal barrier. Transient LES relaxations (TLESRs) lead to reflux as these vagally mediated motor patterns cause relaxation of the LES and also result in oesophageal shortening and inhibition of the crural diaphragm. Heartburn and regurgitation are the characteristic symptoms of GERD. A clinical diagnosis of GERD can be made with typical symptoms. Oesophagitis is seen in a minority of patients with GERD. Lifestyle modification is widely advocated for patients with GERD. For short-term relief of symptoms of mild GERD, antacids/alginates are frequently used but they do not heal oesophagitis. Both histamine 2 receptor antagonists (H2RA) and proton pump inhibitors (PPI) have been shown to heal and prevent relapse of oesophagitis, although PPIs have been shown to be superior. The PPIs are the recommended first-line therapy for erosive oesophagitis and initial management of non-erosive reflux disease. Maintenance PPI therapy should be given to patients with oesophagitis, those who have recurrence of symptoms after discontinuation of medication and for those with complications of GERD.