Localization is an important topic in wireless sensor networks because sensor nodes are randomly scattered over a region and can get connected into a network on their own. Adjusting the transmission power levels has an important impact on energy efficiency and network lifetime in wireless sensor networks. in this work, we proposed a localization protocol with an adaptive power control in wireless sensor networks. Each node can transmit beacon packets at different power levels. Whenever a node receives beacon packets transferred at different power levels, it will adaptively select a beacon packet to estimate the distance to the landmark. When a sensor node has estimated the distances to three landmarks, it can compute for its location using triangulation. Simulation results showed that the proposed algorithm can improve the error rate of localization. (c) 2008 Elsevier B.V. All rights reserved.