To increase the diagnostic possibilities, the authors suggested a method of endoscopic examination of patients with esophageal strictures by means of a superthin PF-28 fibroscope produced by the Olympus firm (Japan), which was introduced along a string-guide. The examination was successful in 24 of 26 patients. Clinical observations have shown that esophagogastroscopy with a superthin endoscope makes it possible to recognize the exact length of the stenosed segment, detect the second zone of stenosis, and determine the condition of the mucous membrane of the esophago-gastric junction and the proximal part of the stomach.