One of the major problems that a national health system face is the lack of a unified clinical data management. In Greece, the critical and sensitive medical data generated during a patient lifetime are fragmented in one or more hospitals and healthcare services are not characterized by a 'continuity' factor. There is not the appropriate technological and administrative infrastructure for a unified patient medical history, prescriptions, laboratory tests or therapeutic plan. Technological, administrative and economic factors have led to this situation. We propose the integration and implementation of a blockchain network as a complementary technology to the existing information systems, so reliable and effective information management could be provided by a healthcare organization or the national healthcare system. Blockchain technology could be implemented as a bridge that can provide information systems interoperability within a hospital or between different hospitals.