Plain film radiographs and computed tomography scans of sacroiliac joints in 65 asymptomatic patients with known inflammatory bowel disease were performed and evaluated by two radiologists. Computed tomography revealed the presence of asymptomatic sacroiliitis in 21 (32%) of the 65 patients (New York grades 2 to 4); asymptomatic sacroiliitis was identified by plain film radiography in only 10 (18%) of 57 patients (p < 0.001). No correlation was observed between the presence or absence of sacroiliitis, and the age and sex of patients, disease type, or duration of disease. The prevalence and diagnostic value of computed tomography in the detection of asymptomatic sacroiliitis in patients with inflammatory bowel disease are discussed.