The paper presents an agent-based architecture of the virtual enterprise (VE) and a model for production planning. The partners of the VE, modelled as nodes of the VE (denoted NEV), use negotiation and mediation principles to collaboratively elaborate consistent production plans. The proposed architecture of the VE is a set of levels corresponding to production cycles of products to be delivered by the VE to the customers. A multi-agent system is used to model the VE. For each level, a negotiator agent negotiates with the NEVs of the same level. Each NEV is able to locally elaborate direct and backward planning on the basis of an iterative planning model taking into account variation of demands and forecasts to guarantee a global benefit of the entire virtual enterprise. || Ce papier présente une architecture multi-agents d'entreprise virtuelle et un modèle pour planifier la production. Les partenaires de l'entreprise virtuelle (EV), modélisés comme des noeuds de l'EV (NEV), utilise des principes de négociation et de médiati