Governments are searching for ways to improve the equity, efficiency, effectiveness, and responsiveness of their health systems. In recent years there has been an acceptance of the important role of primary health care in helping to achieve these aims. However, there have been no systematic reviews on primary care versus specialist-oriented systems, nor has the case for primary health care been firmly established. This review presents the evidence for the advantages and disadvantages of restructuring a health care system on primary care services. It is based on a rapid but systematic review of key sources of published literature. The evaluation of evidence is complex for a number of reasons, including differing definitions of services, staff and the boundaries between primary and secondary care, changing organizational structures, and an increasing reliance on primary care teams. No studies were found that specifically addressed the advantages of health care systems relying on specialists.