Serum selenium, copper, and zinc levels were studied in 47 patients with Crohn's disease, 117 patients with ulcerative colitis, and 123 age- and sex-matched healthy controls. Serum selenium levels were lower and serum copper levels were higher in men and women with Crohn's disease than in controls (p < 0.001 and p < 0.01, respectively). Trace element levels were not significantly influenced by extent or localization of Crohn's disease. Men and women with ulcerative colitis had higher levels of copper and zinc than did controls (p < 0.01 and p < 0.05, respectively). Men with pancolitis had significantly lower selenium and higher copper levels than men with proctitis. The implications of abnormal trace element status in patients with inflammatory bowel disease are discussed.