BACKGROUND & AIMS: Most previous population-based studies of mortality in inflammatory bowel disease (IBD) did not account for medication use. We evaluated mortality by IBD medication use among members of the Kaiser Permanente Northern California IBD Registry. METHODS: The retrospective, population-based cohort study included 9032 persons who received at least one inpatient or 2 outpatient diagnoses of IBD during 1996-2002. Age and sex standardized mortality ratios measured the associations between IBD and all-cause and cause-specific mortality. Age, sex, and smoking adjusted odds ratios measured the association of mortality by IBD medication use. RESULTS: Compared with health plan members without IBD, mortality was increased in patients with Crohn’s disease (CD) (1.4; 95% confidence interval, 1.2-1.6) but not ulcerative colitis (UC) (1.0; 95% CI, 0.9-1.2). CD was associated with increased mortality from infectious and parasitic diseases (4.1; 95% CI, 1.7-8.5), septicemia (6.8; 95% CI, 2.2-15.8), small intestinal cancer (48.1; 95% CI, 5.8-17.4), respiratory diseases (1.9; 95% CI, 1.3-2.7), digestive diseases other than IBD (2.4; 95% CI, 1.0-4.8), and liver diseases (2.6; 95% CI, 1.0-5.3). UC was associated with increased mortality from digestive diseases other than IBD (3.9; 95% CI, 2.4-6.0). The relationship with CD mortality was 0.7 for aminosalicylates (95% CI, 0.5-1.1), 1.3 (95% CI, 0.9-1.9) for immunomodulators, and 1.0 (95% CI, 0.7-1.4) for corticosteroids. Among patients with UC, these odds ratios were 0.8 (95% CI, 0.5-1.1) for aminosalicylates, 0.5 (95% CI, 0.3-0.9) for immunomodulators, and 0.8 (95% CI, 0.6-1.1) for corticosteroids. CONCLUSIONS: Mortality is increased in CD. Infections, respiratory diseases, and digestive diseases are important specific causes of death. IBD medication use has varying associations with mortality.