Abstract: The study aims to apply one of the artificial intelligence technical called expert systems to develop a medical expert system for the diagnosis of ear problems in children. The expert system described in this paper is able to detect and gives a diagnosis of eleven types of ear problems as well as proper advice for treatment of ear problems in children. The knowledge of the proposed system is collected from two different sources. The first primary source is the medical knowledge of expert doctors. The second source is from specialized databases, books and electronic medical websites. Visual Basic. Net language is used as a tool for designing the proposed system. The proposed system has been tested and evaluated successfully and positive feedback was achieved. In conclusion, it hopes that, it could have contributed to the construction of a medical expert system that meets the demands of all the beneficiaries.Expert systems; ear problems; medical diagnosis; knowledge based system.