Background/purpose: Taiwan has one of the fastest growing aging populations in the world, which makes the effective allocation of scarce medical resources a key issue. This paper investigates patterns in the use of outpatient services by elderly individuals in Taiwan under the National Health Insurance (NHI) program. Methods: We assembled a random sample from the NHI Research Database in Taiwan, comprising 50% of all claims made for elderly people (65 years old) in 2010 (n 1,239,836 beneficiaries) including 14 variables. Results: In 2010, individuals aged 65 years or older comprised 10.74% of the population of Taiwan, and accounted for 11.39% of all physician and outpatient visits. The rate of medical care visits was 28.54 ± 21.23 (Standard deviation) times per person per annum, with a higher rate for women, those in the 80-84 age group, low-income beneficiaries, and the inhabitants of offshore islands. The three most frequent diagnoses for elderly patients were hypertension, diabetes, and acute upper respiratory infections. The mean insured medical costs per person per annum were US Dollars 1,132, with higher expenses for men, those in the 80-84 age group, and those inhabiting urban areas. Conclusion: This study employed nationally representative data in the detection of patterns in outpatient care utilization by elderly individuals in Taiwan. Medical care providers and policymakers should be fully aware of the complex patterns unique to older patients. The results of this study could be used as a benchmark with which to assess the impact of future medical care policy on elderly people.