This article examines the impact of the Health and Social Care Act 2012 on the regulation of competition in the English National Health Service (NHS), by focussing on the change it marked from a system of sector-specific regulation to one which is clearly based in competition law. It has been suggested that the Act and its associated reforms would significantly alter accountability in the NHS, and would change decisions from the remit of public policy to that of the law. To assess the impact the Act has had in practice, the article compares the interpretation of the rules regarding competition in the NHS by the regulators of competition immediately before, and following, the passing of the Act. It argues that, whilst the reforms have the potential significantly to alter the way competition in the NHS is regulated, the impact of the reforms in this area is limited by the development of systems within the NHS to manage and resolve issues internally where possible.