Handedness has been reported to be associated with several disorders, including “immune disease.” We examined the specific association between left-handedness and inflammatory bowel disease in 213 persons. We personally questioned 43 patients with Crohn's disease, 40 with ulcerative colitis, 70 control patients with various gastrointestinal disorders, and 60 hospital employees with no known immune or gastrointestinal disorder. The clinical diagnosis of each patient was rigorously established. Handedness was determined by The Oldfield Inventory. Study groups were well matched for age, sex, socioeconomic, and cultural backgrounds. The incidence of left-handedness among these groups was 9.3% for those with Crohn's disease, 15.0% among those with ulcerative colitis, 11.4% and 13.3% among the control groups, respectively. There was no excess of left-handedness, within any subgroup, when those with inflammatory bowel disease were analyzed according to sex; or disease location, duration, or overall severity. Our data do not confirm the previously suggested association of lefthandedness and inflammatory bowel disease.