This study examined the impact of duration of physician-patient ties on the processes and costs of medical care. The analyses used a nationally representative sample of Americans 65 years old or older who participated in the Medicare Current Beneficiary Survey in 1991 and had a usual source of care. Older Americans have long-standing ties with their physicians; among those with a usual source of care, 35.8% had ties enduring 10 years or more. Longer ties were associated with a decreased likelihood of hospitalization and lower costs. Compared with patients with a tie of 1 year or less, patients with ties of 10 years or more incurred $316.78 less in Part B Medicare costs, after adjustment for key demographic and health characteristics. However, substantial impacts on the use of selected preventive care services and the adoption of certain healthy behaviors were not observed. This preliminary study suggests that long-standing physician-patient ties foster less expensive, less intensive medical care. Further studies are needed to confirm these findings and to understand how duration of tie influences the processes and outcomes of care.