Background: Hiatus herniae are commonly seen at endoscopy. Many patients with a large hiatus hernia are endoscoped for symptoms associated with the hernia and many of these will progress to surgical treatment. However, little is known about the natural history of small to medium size hiatus herniae, and their risk of progressing to a larger hernia requiring surgery. This study aims to determine the need for subsequent surgery in these patients. Methods: A retrospective audit of the endoscopy database at Flinders Medical Centre and the Repatriation General Hospital in Adelaide, South Australia for the 2-year period 2002–2003 was performed to identify all patients with a hiatus hernia. Patients under the age of 65 and with a sliding hiatus hernia <5 cm in length were selected for this study, and sent a questionnaire which determines the long-term (>10 years) outcome of these herniae. Results: Small- to medium-sized hiatus herniae (<5 cm length) were found at 10% of endoscopies performed. In this group, 38% had reflux as the indication for endoscopy. 1.5% subsequently progressed to anti-reflux surgery or hiatus hernia repair. Thirty-nine percent reported being on proton pump inhibitors for symptom control. No patients required emergency surgical repair of their hiatus hernia. Conclusion: While patients with small- to medium-sized sliding hiatus hernia commonly have symptomatic reflux, an acute problem requiring emergency surgery is unlikely over long-term follow-up.