Enterprise Application Integration (EAI) is still facing the crucial semantic integration problem. This latter is not correctly addressed by today's EAI solutions that focus mainly on the technical and syntactical integration. Addressing the semantic integration level will promote EAI by providing it more consistency and robustness. Some efforts are suggested to solve the semantic integration problem, but they are still not mature. This paper deals with semantic problem in EAI and will present an ontology-based approach in order to overcome some issues of the integration problem.