Electronic medical records (EMRs) are critical, highly sen-sitive private information in healthcare, and need to be frequently shared among peers. Blockchain provides a shared, immutable and transparent history of all the transactions to build applications with trustability, accountability and transparency. This provides a unique opportunity to develop a secure and trustable EMR data management and sharing system by using blockchain. We present our perspectives on blockchain-based health care data management. We implemented a framework for managing and sharing EMR data on cancer patient care that ensures privacy, security, availability, and fine-grained access control over EMR data.