The scope of the experts system is very limited. It cannot work outside the field it is being used. The users knowledge is required to adjust to new situation. To reduce the rigidity of the experts systems human expertise is required. The expert should be able to describe what the does then some of his expertise can be recorded in expert system. The process of clarifying recording and refining expertise is known as knowledge Engineering and the professionals involved are called as knowledge engineers. Thus experts systems provides ample opportunities for the knowledge engineers.