Some evidence links cancer outcomes to place of service, but the influence of NCI (National Cancer Institute) cancer centers on outcomes has not been established. We compared mortality for NCI cancer center attendees versus nonattendees. This retrospective cohort study included individuals with incident cancers of the lung, breast, colon/rectum, or prostate from 1998 to 2002 (N = 211,084) from SEER (Surveillance, Epidemiology, and End Results)-Medicare linked data, with claims through 2003. We examined the relation of NCI cancer center attendance with 1- and 3-year all-cause and cancer-specific mortality using multilevel logistic regression models. NCI cancer center attendance was associated with a significant reduction in the odds of 1- and 3-year all-cause and cancer-specific mortality. The mortality risk reduction associated with NCI cancer center attendance was most apparent in late-stage cancers and was evident across all levels of comorbidities. Attendance at NCI cancer centers is associated with a significant survival benefit for the four major cancers among Medicare beneficiaries.