Background/aims: Although there are many studies reporting that colonic dysplasia and cancer develop more frequently in ulcerative colitis patients with ulcerative colitis with primary sclerosing cholangitis, there are insufficient data on the course of the colonic disease. In this study, the course of the colonic disease in ulcerative colitis patients with primary sclerosing cholangitis was investigated. Methods: Data obtained from ten patients with total colitis and accompanying primary sclerosing cholangitis (three females, seven males, mean age: 44.5±10.0 years) were compared with data obtained from 64 patients with pancolitis but without primary sclerosing cholangitis (27 females, 37 males; mean age: 42.3±17.1 years). Results: The follow-up period was 6.4±6.2 years in patients without primary sclerosing cholangitis, 12.7±6.2 years in total and 5.1±4.0 years (after development of the condition) in patients with primary sclerosing cholangitis (p<0.01). The number of disease attacks (3.7 attacks/yr vs. 0.5 attacks/yr), duration of the active disease (12.9±8.0 months vs. 0,3±1.0 months), the number of patients in whom corticosteroids were used (47 patients vs. one patient), the number of patients hospitalized (50 patients vs. one patient) and duration of hospitalization (1.2±0.8 months vs. 0,1±03 months) were higher in patients with than without primary sclerosing cholangitis (after development of the condition) (p<0.001). There was no significant difference in data obtained from patients with and without primary sclerosing cholangitis before development of the disease. Conclusions: Colonic disease subsides when primary sclerosing cholangitis develops. The higher frequency of colonic dysplasia and cancer seen in patients with primary sclerosing cholangitis can be explained by the fact that most of them have a longer duration of total colitis and fewer need total colectomy. Even though it does not seem to cause clinical problems, the colonic disease should not be ignored in these patients.