A 66-year-old man patient with chronic hepatitis (CH) C and complications from ulcerative colitis (UC) was treated with interferon-beta (IFN-beta). Endoscopically, the UC disease activity was moderate before IFN-beta treatment but was in remission eight week after treatment. However, a few months after stopping IFN treatment, endoscopy revealed that the UC disease activity had returned to moderate levels. This result shows that UC improved with IFN treatment.