Majority of published data describing endocytoscopic examination of upper gastrointestinal tract mucosa, but in recent publications, it is reported, that endocytoscopy is suitable for small bowel, colon, respiratory tract and even peritoneum "optical biopsy". In number of articles possibilities of celiac sprue diagnostics with endocytoscopy is discussed, but small-bowel endocytoscopy is limited, due to absence of endocytoscopes, compatible with enteroscopes. More widely endocytoscopy is used in colon, mostly in lateral-spreading adenomas diagnostics. Prof. S-E. Kudo developed endocytoscopic classification of colonic mucosa changes, used for differential diagnostics and lesion mapping, describing hyperplasia, adenomas with different grades of intraepithelial neoplasia, non-invasive and invasive cancer. Some authors reported about good possibilities of endocytoscopy in inflammatory bowel disease diagnostics. Most of data, related to respiratory tract endocytoscopic examination, focused on precancerous conditions and early pharyngeal and lung cancer, and the preliminary results are promising, but, unfortunately, for now, endocytoscopy in bronchial tree is limited, due to lack of thin endocytoscopes. According to some article data, it is possible to use endocytoscopy not only in gastrointestinal and respiratory tract, but also in optical confirmation of peritoneal tumor dissemination in gastric and ovarian cancer patients, and--in bladder mucosa examination.