The independent right-of-centre thinktank Civitas says more could be done using market-style reforms but this is being hampered by central control from Government and a failure by health chiefs to use the powers at their disposal.
Competition was first introduced in the NHS under reforms in 1991 and has since been increasingly embedded in the NHS as part of efforts to drive efficiencies and make services respond to patients.
Civitas says market forces have contributed to improved access for patients, reduced waiting times and increased efficiency in hospitals. But it warns the benefits are not widespread and hospitals remain more powerful than primary care trusts (PCTs) which pay for services.
Report author Laura Brereton said: "While there have been improvements, they are not clearly attributable to market-based reforms. The NHS appears to be in the unfortunate position of taking on the extra costs of competition without realising the benefits."
The thinktank said PCTs lacked skills to drive performance and purchase services effectively, were reluctant to break historic patterns of purchasing care and afraid to stand up to hospitals.
Some GPs had taken charge of commissioning services to good effect but many were interested in only providing services themselves rather than innovating.
It found increased choice for patients had contributed to decreases in waiting times, but the uptake of choice was not widespread and information for patients was poor.