The monitoring of patients with ulcerative colitis is easier than in patients with Crohn's disease for several reasons: the severity of symptoms and activity of inflammation tend to run parallel in ulcerative colitis when involvement of the large bowel is more extensive. The easy accessibility of the colonic mucosa by endoscopic and histologic examination provides further information concerning the degree of inflammation. In severe attacks, the patient must be admitted to hospital and monitored carefully. Clinical and laboratory parameters (such as daily stools, CRP, fever, haemoglobin, albumin, etc.) and plain abdominal X-ray are useful in monitoring the activity of the disease and to predict the outcome. In mild to moderate attacks, endoscopic and histologic evaluation are the best methods for choosing the appropriate treatment and for assessing response.