Wireless sensor nodes need to know their localizations in many control and monitoring applications such as routing, target tracking, etc ... To determine node localization, many techniques have been proposed in the literature. This paper proposes a rule-based method, called MuR (Method using Rules), that allows to locating nodes with high accuracy. The rules are based on information of located nodes (called anchors). They resolve ambiguity when a node can be located at more than one position. MuR is compatible with existing localization techniques; it can be used as a preliminary step before the execution of one of these techniques. Simulation results show the effectiveness of MuR locating a maximum number of nodes. Index Terms—wireless sensor networks, localization, positionning, accuracy.