This report describes a case of right-sided ulcerative colitis in which multiple shallow ulcers and erosion with symmetric luminal stenosis were distributed segmentally from the ascending colon to the cecum, with a skip lesion composed of superficial erosions in the right half of the transverse colon. Both the rectum and the left colon were spared at the time of onset. Biopsies taken from the lesions showed non-specific inflammation, while those from the rectum and sigmoid colon showed no abnormal findings. A 5-year follow-up study was made based on radiography and endoscopy. Other inflammatory bowel diseases, such as Crohn's disease, tuberculosis, Yersinosis, Behçet's disease, and ischemic colitis were all ruled out, based on the macroscopic and microscopic findings as well as the clinical course. To our knowledge, this is the first report of right-sided ulcerative colitis that has been followed for a long period.