The purpose of this study is to determine the incidence of venous thromboembolism (VTE) in patients with ulcerative colitis and patients with Crohn disease. The number of patients discharged from hospitals throughout the United States with a diagnostic code for ulcerative colitis and for Crohn disease from 1979 through 2005 was obtained from the National Hospital Discharge Survey. The incidence of VTE among medical patients with ulcerative colitis was 21 000 of 1 129 000 (1.85%) and among medical patients who had no inflammatory bowel disease, the incidence was 10 421 000 of 918 570 000 (1.13%; relative risk 1.64, 95% confidence interval [CI] = 1.62-1.66). The incidence of VTE among medical patients with Crohn disease was less than those with ulcerative colitis, 22 000 of 1 803 000 (1.22%). The risk, compared with patients who did not have inflammatory bowel disease, was only marginally increased (relative risk 1.08, 95% CI = 1.06-1.09).