A mobile ad hoc network (MANET) is a temporary infrastructureless network, formed by a set of mobile hosts that dynamically establish their own network on the fly without relying on any central administration. Mobile hosts used in MANET have to ensure the services ensured by the powerful fixed infrastructure in traditional networks, the packet forwarding is one of these services. Resource limitation of MANET's nodes, particulary in energy supply, along with the multi-hop nature of these networks may cause a new problem that does not exist in traditional networks. To save its energy a node may behave selfishly (no-cooperatively), thus it misbehaves by not forwarding packets originated from other nodes, while using their resources to forward its own packets to remote recipients. Such a behavior hugely threatens the QoS (Quality of Service), and particulary the packet forwarding service availability. Some solutions for selfish nodes detection have been recently proposed, but almost all these solutions rely on the monitoring in the promiscuous mode technique of the watchdog , which suffers from many problems especially when using the power control technique. In this paper we propose a new approach to detect selfish nodes unwilling to participate in packet forwarding, that mitigates some watchdog's problems. We also assess the performance of our solution by simulation. © Springer-Verlag Berlin Heidelberg 2005.