Objective To evaluate the clinical and endoscopic features of ulcerative colitis(UC). Methods The cases of UC were collected from 1975 to 2001. According to the diagnostic criteria of Chengdu conference, 486 and 490 patients were diagnosed as UC in our hospital from 1975 to 1994 and from 1995 to 2001 respectively. Their records were retrieved and the data were analyzed for sex, age, presentation, the course of the illness and lesion range. Results In the two groups from 1975 to 1994 and from 1995 to 2001, the proportion of patients diagnosed as UC under colonoscopy was increased from 3.51% to 4.44%. The ratio of male to female was 1.67 and 1.25 respectively. The mean age at the diagnosis increased from 42.4 years old to 51.5 years old, and the peak age was between 30 and 49 years old, between 40 and 49 years old and greater than 60 years old respectively. The typical clinical manifestations of UC were bloody mucopurulent stool, diarrhea and abdominal pain. Proctosigmoiditis or proctitis was found in 269 patients (55.4%) and 316(64.5%), left side colitis in 84(17.3%) and 68(13.9%), pancoltitis in 58( 11.9% ) and 70(14.3%) respectively. In the two groups, there were 437( 89.9% ) and 443(90.4%) patients who had the course of less than 10 years respectively. The definitive diagnosis of UC was dependent on biopsy. Conclusions The lesions of UC are commonly located in the left side colon, the course of UC is short, the age of onset is relatively high in the middle and old aged group, and the prevalence of both malignancy and complications is low. Colonoscopy with biopsy is considered to be the major means for the diagnosis of UC.