BACKGROUND: The exact definition of natural history is important in ulcerative colitis for both clinicians and patients, because it may play a role in the development of treatment strategies for physicians and in the future prospect for patients. In this study, we review the clinical evolution of patients with ulcerative colitis and document the probable risk factors that make the patients undergo colectomy. METHOD: The patients with ulcerative colitis followed in our gastroenterology department between 1993 and 2003 were retrospectively reviewed. FINDINGS: Early age at the onset of disease was found to be related to higher endoscopic disease activity and more frequent colectomy. Colectomy was also more frequent in pancolitis and extensive colitis. CONCLUSION: Early onset of ulcerative colitis and extensive disease are among the most remarkable determinant factors affecting the indication for colectomy (Fig. 2, Tab. 15, Ref. 16). Full Text (Free, PDF) www.bmj.sk.