There is a large body of evidence that user fees in the health sector create exclusion. Health equity funds attempt to improve access to health care services for the poorest by paying the provider on their behalf. This paper reviews four hospital-based health equity funds in Cambodia and draws lessons for future operations. It investigates the practical questions of 'who should do what and how'. It presents, in a comparative framework, similarities and differences in objectives, the actors involved, design aspects and functional modalities between the health equity funds. The results of this review are presented along the lines of identification, hospitalization rates and relative costs. The four schemes had a positive impact on the volume of utilization of hospital services by the poorest patients. They now account for 7 to 52% of total hospital use. The utilization of hospitals by paying patients has remained constant in the same period. The comparative review shows that a range of operational arrangements may be adopted to achieve the health equity fund objectives. Our study identifies essential design aspects, and leaves different options open for others.