In web-based education there is an emphasis on reusing and sharing instructional content due to the complexity of the development process of highquality learning materials. It leads to the learning objects orientation as well as to partnerships among institutions to promote sharing of these objects. In order to contribute to these efforts, we proposed an architecture based on the mediators and wrappers for integrating learning objects repositories. The components of this architecture were implemented by the use of web- services and the integration processes were enriched by ontologies. The use of mediators allows a query to be redefined as sub-queries that are distributed to the data sources and the results to be integrated. The wrappers allow the data sources to understand the sub-queries and the mediator to understand the respective answers. The implementation of the architecture components as web services allows more flexibility and interoperability among the participants of the community. The formalism of ontologies is used to deal with the semantic heterogeneity as the metadata concepts of each repository are described and the equivalences are established. The development of this architecture is called LORIS, an integration system of learning objects` repositories. LORIS is being adopted by PGL, an international partnership project for promoting web-based education.