Negotiation plays a key role as a means for sharing information and resources with the aim of looking for a common agreement. This paper proposes a new approach based on possibility theory, which integrates both the merits of argumentation-based negotiation and of heuristic methods looking for making trade-offs. Possibilistic logic is used as a unified setting, which proves to be convenient not only for representing the mental states of the agents (beliefs possibly pervaded with uncertainty, and prioritized goals), but also for revising the belief bases and for describing the decision procedure for selecting a new offer. Key words: Multi-agents systems, Negotiation, Possibilistic logic, Argumentation.