Healthcare is one of the application domains that uses blockchain and IoT Technology. Nowadays healthcare sector is facing the main challenge in distributing electronic health records, which is data privacy. It has been difficult to manage the large-scale data while preserving the privacy of patients. Blockchain is an emerging technology with great potential for improving the efficiency, security, and privacy of Electronic Health record (EHR) sharing systems. For an individual, self-health diagnosis by keeping a close watch on health parameters via smart wearable technology in real time helps with prior disease prediction. In this chapter, we present a detailed overview of healthcare applications of IoT, blockchain, and machine learning along with the literature survey, and we will try to point out gaps and the scope of research for desiring researchers on existing healthcare applications. We will also discuss the challenges and issues of healthcare applications based on machine learning, blockchain, and IoT, such as data security, privacy, interoperability, single point of failure, scalability, and data integrity, and present the associated research challenges.