Data from the National Death Index (NDI) are frequently used to determine survival status in epidemiologic or clinical studies. On the basis of selected information submitted by the investigator, NDI returns a file containing a set of candidate matches. Although NDI deems some matches as perfect, multiple candidate matches may be available for other cases. Working across data from the Duke University site of the Established Populations for Epidemiologic Studies of the Elderly (EPESE), NDI, and the Social Security Death Index (SSDI), the authors found that, for this Established Populations for Epidemiologic Studies of the Elderly cohort of 1,896 cases born before 1922 and alive as of January 1, 1999, a match on Social Security number plus additional personal information (specific combinations of last name, first name, month of birth, day of birth) resulted in agreement between NDI and Social Security Death Index dates of death 94.7% of the time, while comparable agreement was found for only 12.3% of candidate decedents who did not have the required combination of information. Thus, an easy to apply algorithm facilitates accurate identification of NDI matches.