The Department of Veterans Affairs maintains a computerized patient treatment file that contains all records from veterans treated as inpatients in VA hospitals distributed throughout the United States. Using the patient treatment files from 1986 to 1989, the present study takes advantage of this large national data set to examine demographic and geographic associations of inflammatory bowel disease. Inflammatory bowel disease tended to affect predominantly female, white, and younger veterans, these trends being more marked in cases of Crohn's disease than ulcerative colitis. Hospital discharges secondary to both Crohn's disease and ulcerative colitis appeared to be more frequent in veterans from northern than southern parts of the United States, but did not show a seasonal variation different from the general pattern of all other diagnoses. The results in veterans confirm observations made in other studies and suggest that inflammatory bowel disease among different populations is modulated by similar pathophysiologic mechanisms and environmental risk factors.