Endoscopic examination using a specially designed sonde-type small intestinal fiberscope (SSIF, Olympus) was performed in 37 patients of our clinic. The improvement of the scope has enabled us to observe the greater parts of the small intestine within a short time and without hazard to the patient. Therefore, with further improvement of this instrument and the insertion technique, we will be able to inspect all parts of the small intestinal mucosa and diagnose the lesions more easily.