Background: Observed racial disparities in diverticulitis surgery have been attributed to differences in health insurance status and medical comorbidity. Objective: To examine disparities in procedure type (elective vs urgent/emergency) and mortality in patients with surgically treated diverticulitis insured by Medicare, accounting for comorbidities. Design: Retrospective analysis of Medicare Provider Analysis and Review inpatient data. Patients: All blacks and whites 65 years and older undergoing surgical treatment for primary diverticulitis with complete admission and outcome data were eligible. Main Outcome Measures: In-hospital mortality was examined across procedure categories (elective vs urgent/emergency). Multivariable regression controlled for age, sex, and medical comorbidity (Charlson Comorbidity Index). Results: A total of 49 937 whites and 2283 blacks met the study criteria. Blacks were slightly younger (74.7 vs 75.5 years, P<.001) and more likely to be female (75.2% vs 69.8%, P<.001). Blacks carried greater comorbidity than did whites (mean Charlson Comorbidity Index score: 0.98 vs 0.87, P<.001); 67.8% of blacks vs 54.7% of whites (P<.001) were urgent/emergency. After adjustment, blacks demonstrated 26% greater risk of urgent/emergency admission (relative risk, 1.26; 95% CI, 1.22-1.30). Black race was also associated with a 28% greater risk of mortality (relative risk, 1.28; 95% CI, 1.10-1.51). Conclusions: Blacks underwent urgent/emergency surgery more often than did whites. Blacks demonstrated significantly increased mortality risk after controlling for age, sex, and comorbidities. These findings suggest that observed racial disparities encompass more than just insurance status and medical comorbidity. Mechanisms leading to worse outcomes for blacks must be elucidated.