South Korea introduced mandatory social health insurance for industrial workers in large corporations in 1977, and extended it incrementally to the self-employed until it covered the entire population in 1989. Thirty years of national health insurance in Korea can provide valuable lessons on key issues in health care financing policy which now face many low- and middle-income countries aiming to achieve universal health care coverage, such as: tax versus social health insurance; population and benefit coverage; single scheme versus multiple schemes; purchasing and provider payment method; and the role of politics and political commitment. National health insurance in Korea has been successful in mobilizing resources for health care, rapidly extending population coverage, effectively pooling public and private resources to purchase health care for the entire population, and containing health care expenditure. However, there are also challenges posed by the dominance of private providers paid by fee-for-service, the rapid aging of the population, and the public-private mix related to private health insurance.