Abstract: “Big Data” is a new paradigm that is introduced in the field of computer science to abstract the size of data. It refers to huge quantities of data which need special processes according to business requirements. To get exact information and gain knowledge, professionals must apply intelligent tools, technologies and methodologies in the field’s major areas. Yearly a lot of people lost their life because of medical mistakes. Diagnosing and treating patient’s case is crucial matter to the medical team. Providers should deliver more accurate and personalized clinical data to improve the quality and efficiency of care. This paper discusses big data term in medical sector and how to analyze this clinical big datasets to discover knowledge to use it in clinical prediction. We discuss the deployment and the new trends with big data and explore two paradigms on building real data infrastructure for future studies and review some of on-line health care applications. Afterward, this paper propose framework which figure-out how to analyze big data and how to discover knowledge from the extracted information. Knowledge discovery and data mining are correlated terms; data mining is a step in knowledge acquisition processing journey, it is about applying data analysis and discovery algorithms, which should convey the widespread growth of data collection. As conclusion, big data analysis is expected to reveal the knowledge structure which guided the decisions making.