A 29-year-old woman with Behçet's syndrome developed a severe colitis that ultimately required colectomy. The colectomy specimen showed extensive mucosal ulceration with varying longitudinal, fissuring, and aphthoid configurations, usually occurring within a background of normal or focally inflamed mucosa, and associated with a lymphocytic vasculitis involving submucosal veins. A review of the literature reveals 29 additional cases of colitis complicating Behçet's syndrome. The colitis is characterized by multiple ulcers of diverse size, appearance, and depth of penetration involving any portion of the large bowel, occasionally with coexistent ileal or anal disease. Vasculitis may be the underlying process. Although it resembles other types of colitis, particularly Crohn's colitis, differences in clinical and pathologic features suggest that the colitis of Behçet's syndrome represents a distinct condition.