The Greek medical profession played an important role at the start of the Greek National Health System (NHS) in 1983 and became intrinsic to its later development. In particular, junior hospital doctors firmly established their position and rights as a result of the new NHS. Using archival sources and interviews with elite participants, this article investigates the specific patterns of power and influence that Greek NHS doctors have exerted from the establishment of the Greek NHS through the latest major attempt at reform in 2001 to the present. Hospital doctors, in particular, have been able consistently to resist any health care system reforms that might affect their dominant position. Their unchallenged position in the system derives from both the particularities of the Greek state and society (in particular, the former’s founding institutional arrangements and the latter’s clientelistic social relations) and the key role that junior doctors played in the early stages of the Greek NHS. As a result, the system is highly path dependent in that the initial implementation of the NHS during the 1980s ensured that subsequent reforms consistently favored the self-interest of medical doctors. Though challenges to the unaccountable power of the medical profession have emerged in Greece following the financial crisis of 2009, including the beginnings of a popular critique of the medical profession, it is too soon to tell whether these will succeed in bringing about significant change.