Blockchain technology provides a new way of decentralizing existing systems through its components. The application of blockchain in healthcare has the potential to revamp the existing centralized healthcare information systems. The electronic healthcare records (EHRs) are computerized format of medical records that include the collection of patient data which play a key role in the healthcare information systems. As the healthcare data is constantly shared among different untrusted parties, security of the EHRs is of prime importance, and blockchain provides a way to decentralize and secure the EHR systems. In this light, this thesis studies the role of blockchain as a security mechanism in the management of EHRs through the method of a literature survey. A classification method has been developed using existing works, to classify the literature, and analyse it according to the layered architecture of blockchain and the CIA triad. Through the survey, it is seen that the blockchain technology is a potential security solution for the decentralized management of EHRs, through its components- the consensus mechanism, Merkle tree structures, and public key cryptography. Further, it serves more as an added layer of security to the EHRs, rather than a direct mechanism, because the EHRs are not directly stored on the blockchain. The possible future research direction in this regard, is found in studying in detail the suitable consensus mechanisms for application in EHRs systems, and an evaluation of the technology in a real-world application.