Barrett's oesophagus is a well-recognised premalignant lesion for oesophageal adenocarcinoma. It is present in 1 - 2% of the general population, and 2 - 5% of those with gastro-oesophageal reflux disease. The majority of Barrett's cases within the population are undiagnosed, consequently most cases of oesophageal adenocarcinoma arise de novo. The incidence of oesophageal adenocarcinoma has increased by more than sixfold in the last 30 years. However, most patients with Barrett's oesophagus will not develop oesophageal adenocarcinoma. The major focus of biomarker research in Barrett's oesophagus is to find a marker that is able to identify patients at the highest risk of progressing to adenocarcinoma. Other potential roles include increasing the sensitivity of minimally invasive screening tests to identify patients with Barrett's oesophagus and predicting which patients are most likely to benefit from chemoprevention and endoscopic therapies. In established oesophageal adenocarcinoma, biomarkers would be able to individualise patient management by providing valuable information on patient prognosis and their suitability for novel targeted therapies. This review aims to explore the potential roles of biomarkers in Barrett's oesophagus and oesophageal adenocarcinoma, focusing on the most extensively studied candidates and future novel developments.