We sought to determine the extent to which the Indian Health Service (IHS) identified enrollees who also use the Veterans Health Administration (VHA) as veterans. We used a bivariate analysis of administrative data from fiscal years 2002-2003 to study the target population. Of the 32259 IHS enrollees who received care as veterans in the VHA, only 44% were identified by IHS as veterans. IHS data underestimates the number of veterans, and both IHS and VHA need mechanisms to recognize mutual beneficiaries in order to facilitate better coordination of strategic planning and resource sharing among federal health care agencies.