This document provides an overview of decentralization of health financing and expenditures in OECD countries. It finds that in about half of OECD countries, subnational governments are major players in healthcare systems, financing on average 30% of health expenditures. The share of health expenditures in total subnational government spending has increased since 2000. Specific challenges in decentralized frameworks include the stability and predictability of subnational government revenues, policy setting and central government control over subnational health spending, and other challenges such as revenue volatility and geographic variations.