The clinical, radiological, endoscopic and histological aspects of a case of Isolated Ulcer Syndrome (IUS) of the rectum are examined. For over a decade and on the basis of its clinical, radiological, endoscopic and histological features, this condition was considered Ulcerous Rectocolitis and treated as such. The case presented serves to highlight the possibility of confusing this ulcer with other inflammatory colorectal conditions if only the clinical, radiological and endoscopic pictures are taken into consideration. The importance of histological examination of numerous bioptic samples is emphasised as essential for accurate diagnosis.