This study aimed to determine a conceptual framework of Human Capital and its relations with other related concepts. To achieve these objectives, the study discussed the importance of Human Resources in business organizations, the begging of using Intellectual Capital concept, and its elements, as an approach to identify of Human Capital, its elements, and its relations with Tacit Knowledge and Explicit Knowledge in the organizations. The study discussed also the importance of Human Capital in shade of Knowledge Economy, then moved to show the approaches used in measuring of Human Capital, in addition to the difficulties that may face us in using these approaches. Finally, the study showed a model of relations between Human Capital, Intellectual Capital, Structural Capital, and Customer Capital, and the elements of all of them inspiring from the opinions and theories that showed in the study.