Learning objects offer a new content design methodology for instructional designers in developing and utilizing e-learning environments. These learning objects are usually tagged and stored in repositories in a taxonomicway and mostly accompanied by key-based searching capability. Since those repositories do not have complicated reasoning and inference capabilities, access to and integration of them into an existing course package create a problem for e-learning instructors and learners. These problems will be able to be fixed by integration of semantic web technologies, and current learning object repositories could better be utilized by developing ontology-based learning object retrieval tools. In this chapter, the development and evaluation of an ontology-based learning object navigation and retrieval tool (OBELON) is presented. As part of an evaluation process, OBELON was compared with a taxonomy-based learning object retrieval system by using two information retrieval parameters: precision and recall. The findings indicated that ontology-based system produced more precise and high recall scores.