The study was designed to evaluate the scope of applications of the new digital videoendoscopic NBI-technology for the diagnosis of chronic duodenitis (CD), the prevalence and clinical manifestations of this pathology. Of 287 patients with CD, 102 were examined using a GIF-H180 EVIS Exerall apparatus (Olympus, Japan) equipped with the NBI system. Control patients were examined with conventional fiber-optic and videoendoscopes GIF-Q49 and GIF-Q160 EVIS Exeral (Olympus, Japan). Evaluation encompassed endosopic signs of inflammation, its spread, and severity. It was shown that manifestations of inflammation of duodenic mucosa correlated with the endoscopic picture in the NBI regime and results of histological studies. The use of the NBI-technique in routine oesophagogastroduodenoscopy of patients with CD enhances efficiency of detection of even mild inflammatory reactions in duodenal mucosa from 20 to 72.5% (P < 0.05).