International audienceIn view of the prospects offered by the Wireless Sensor Networks (WSNs), some of the main challenges in recent years concern access to more reliable information (event detection) for an efficient decision making. Moreover, WSNs are one of the most speedily developing information technologies and promise to have a variety of applications in Next Generation Networks (NGN), Internet of Things (IoT), and for critical and safety relevant applications.Reliability is one of the most important attribute of such systems. Thus, in the field of artificial intelligence, the development of intelligent systems for processing imprecise and/or uncertain information is proposed. Truth be told, reliable event detection at the sink node depends on collective information given by source nodes and not just on any individual report. Subsequently, the WSNs world view requires a collective event to the sink reliability notion instead of the conventional end to end notion. This paper analyses the reliability of WSNs by adopting the theory of belief functions. The proposed Transferable Belief Model (TBM) approach aims to analyse reliability in WSNs according to the network topology. It includes a reliability of coverage, reliability of packet delivery, reliability of secure data exchange, reliability of network availability and reliability in terms of network latency