Background. We examined whether older adults who had continuity of care with a primary care physician (PCP) had lower mortality. Methods. Secondary analyses were conducted using baseline interview data (19931994) from the nationally representative Survey on Assets and Health Dynamics among the Oldest Old (AHEAD). The analytic sample included 5,457 self-respondents 70 years old or more who were not enrolled in managed care plans. AHEAD data were linked to Medicare claims for 19912005, providing up to 12 years of follow-up. Two time-dependent measures of continuity addressed whether there was more than an 8-month interval between any two visits to the same PCP during the prior 2-year period. The present exposure measure calculated this criterion on a daily basis and could switch on or off daily, whereas the cumulative exposure measure reflected the percentage of follow-up days, also on a daily basis allowing it to switch on or off daily, for which the criterion was met. Results. Two thousand nine hundred and fifty-four (54%) participants died during the follow-up period. Using the cumulative exposure measure, 27% never had continuity of care, whereas 31%, 20%, 14%, and 8%, respectively, had continuity for 1%33%, 34%67%, 68%99%, and 100% of their follow-up days. Adjusted for demographics, socioeconomic status, social support, health lifestyle, and morbidity, both measures of continuity were associated (p < .001) with lower mortality (adjusted hazard ratios of 0.84 for the present exposure measure and 0.31, 0.39, 0.46, and 0.62, respectively, for the 1%33%, 34%67%, 68%99%, and 100% categories of the cumulative exposure measure). Conclusion. Continuity of care with a PCP, as assessed by two distinct measures, was associated with substantial reductions in long-term mortality.