This chapter investigates how, within a number of European Union (EU) Member States, competition law has been used to address problems of market power in the healthcare services sector. It summarizes the relevant EU and national competition laws and considers the experience of applying those laws to providers of healthcare services. The chapter is chiefly concerned with healthcare services in England, although examples are drawn for other EU Member States. Examination of the English experience provides a view of the use of competition law to address market power problems in most elements of the health system matrix. The chapter then considers three challenges that emerge from that experience of using competition law to address problems of market power in healthcare service markets. The first challenges the applicability of competition law to healthcare service providers operating in each or every element of the healthcare system matrix. The second, accepting applicability, questions the appropriateness of the substantive rules to healthcare services. The third, a battle of authority and autonomy, considers whether decisions made by healthcare service providers should be subject to external review and the type of review that competition law offers.