China's urban health insurance system is mainly consisted of labor insurance schemes (LIS) and government employee insurance scheme (GIS). LIS is a work unit-based self-insurance system that covers medical costs for the workers and often their dependents as well. GIS covers employees of the State institutions, is financed by general revenues. Since 1980s, China has implemented series of health insurance system reforms, culminating in the government's major policy decision in December of 1998 to establish a social insurance program for urban workers. Compared with the old insurance systems under LIS and GIS, the new system expands coverage to private sector employees and provides a more stable financing with its risk pool at the city level. Despite of these advantages, implementation of China's health insurance reform program is faced with several major challenges, including risk transfer from work units to municipal governments, diverse need and demand for health insurance benefits, incongruent roles of the central and regional governments. These challenges may reflect practical difficulties in policy implementation as well as some deficiencies in the original program design.