In this paper, the authors propose a new approach to requirements analysis, call ed OORA (ontology-oriented requirements analysis). The most important feat ure of this approach is that various ontologies have been introduced to represen t relationships between objects and/or classes. These ontologies may significant ly enhance the expressiveness of the current OOA (object-oriented analysis) app roaches. In this paper, first the OORA requirements model is designed. After tha t, two key types of ontologies are illustrated by two typical use cases. Finally , the main phases in OORA are given.