We describe a 42-year-old-man with HIV infection who developed ulcerative colitis. Ulcerative colitis was diagnosed on the basis of clinical symptoms, and the findings of colonoscopy, pathology and culture. Although remission of ulcerative colitis was induced by PSL and SASP, HIV infection progressed. Treatment with highly active antiretroviral therapy (HAART) was started. HIV viral load decreased to less than 50copies/ml and CD4 counts increased to over 400/microl. After discontinuance of PSL and SASP, he is still in good condition. This is the first report of HIV infection associated with ulcerative colitis in Japan. A relationship between immune disorder in advanced HIV infection and inflammatory bowel disease was suggested. Ulcerative colitis might be an important complication in HIV infection.