Recently using information technology in the health care system is an important issue. Medical informatics is the combination of information science, computer science, and health care. As population is increasing rapidly, it is obvious to use medical informatics to save human lives and to treat people in efficient way. Therefore, we tried to explore an overview of the necessities and practical uses of data mining in administrative, clinical, research as well as educational aspects of medical informatics in Bangladesh. It is one the most populous countries in the world and the health care system including data mining in medical informatics is not so handy. Besides, for the effect of monsoon weather people of this country are affected by various diseases but poor investment and weak implementation make these diseases a burden. The study focuses on the needs of clinical data warehousing and the practice of examining these databases in order to improve various aspects of medical informatics in Bangladesh. The study suggests that government and private health care organizations need to take account to store their data and create a research wing in every hospital in Bangladesh as well as other developing countries in the world so that researchers and doctors may be able to find out the solution of their problems. For the greater benefits of the people, more research on medical informatics is essential and implementation of the research outputs must be done in medical treatment.