In wireless sensor networks, hello protocols for neighbor discovery are a basic service offered by the networking stack. However, their study usually rely on rather simplistic models. In this paper we study the impact of radio interferences on neighbor discovery and we introduce an analytical model to estimate the average number of neighbors that a node may expect to discover in his neighborhood. Categories and Subject Descriptors C.2.1 [Computer Communication Networks]: Wireless communications General Terms Performance, Design Keywords Wireless networks, Neighbor discovery, Stochastic geometry, Performance analysis