Ulcerative colitis is an inflammatory disease which, starting from the rectum, affects more or less extended tracts of the colon. Given that distal and extended forms are generally described as a single nosological entity, the authors aimed to verify whether there are any clinical differences between the two groups of patients with varying extents of disease. A retrospective review was made of data relating to 189 patients suffering from ulcerative colitis observed over a 90-months period. Only 111 cases were included in the study: all patients had undergone an endoscopic and histological diagnosis with a follow-up of over one year. Seventy-eight patients (41.26%) were excluded from the study because they had been lost during follow-up, or follow-up had lasted less than one year, or it had not been possible to perform pancolonoscopy. The 111 patients examined were subdivided into 2 groups: one (39 patients) with distal colitis, namely involving the rectum or recto-sigmoid, and the other (72 patients) with more extended disease. The extension of disease was evaluated on the basis of histological findings. The mean follow-up was 5 years and 11 months. The two groups were comparable for age, sex, number of annual attacks, maximum duration of disease-free periods, clinical evolution, predominant symptoms, extraintestinal symptoms and surgical treatment. Results were processed using Student's t test and the chi-square test.(ABSTRACT TRUNCATED AT 250 WORDS)