The biological mechanisms underlying the progression from normal esophageal squamous mucosa to Barrett's epithelium associated with dysplasia and finally to esophageal adenocarcinoma is becoming increasingly well understood. Histologic determination of Barrett's-associated dysplasia remains of paramount importance; however, genetic and biochemical biomarkers of Barrett's metaplasia and dysplasia will facilitate clinical diagnosis, endoscopic surveillance, and monitoring of new therapeutic interventions as they evolve. This article covers conventional and novel biomarkers in Barrett's esophagus.