The Montreal definition and classification of gastroesophageal reflux disease (GERD) clarify the criteria necessary for the a diagnosis of GERD, define esophageal and extraesophageal symptoms, simplify disease management and provide a basis for a universally accepted terminology. GERD is defined as a condition which develops when the reflux of stomach content causes troublesome symptoms and/or complications. The Los Angeles classification is the most recently developed system for the grading of reflux esophagitis and it describes the extent of esophagitis independently of the other measures of severity in a clear, simple and reproducible way. There is strong evidence that visible breaks in the mucosa are the most reliable endoscopic sign of esophagitis. The aim of the study was to investigate the prevalence of reflux esophagitis in adult patients referred to upper gastrointestinal endoscopy from primary care. All outpatient upper gastrointestinal endoscopies performed at the endoscopy unit at Tartu University Hospital, Division of Endocrinology and Gastroenterology, from January 1, 2006 to June 30, 2006 were analysed. Altogether 948 consecutive patients were investigated. Reflux esophagitis was defined endoscopically by visible breaks in the distal esophageal mucosa and severity was graded using the Los Angeles scoring system. Reflux esophagitis was the most common endoscopic finding (15.6%) with the majority of the patients classified as Los Angeles grade A or B (60.1% and 34.5%, respectively). More severe Los Angeles, grades C and D were reported in 4.7% and 0.7% of the reflux esophagitis patients. Los Angeles grade D was diagnosed in only 0.1% of the whole study population. The overall prevalence of clinically significant findings, when limited to reflux esophagitis, peptic ulcer and malignancies, was 32% (15.6% of the patients had reflux esophagitis,12.2% had duodenal ulcer, 3.5% had gastric ulcer, 0.6% had gastric adenocarcinoma, and had 0.1% esophageal squamous cell carcinoma).