In this paper, we present an Energy Efficient Secure Routing Protocol for Sensor Networks (ESecRout). The protocol uses the symmetric cryptography to secure messages, and uses a small cache in sensor nodes to record the partial routing path (previous and next nodes) to the destination. It guarantees that the destination will be able to identify and discard the tampered messages and ensure that the messages received are not tampered with. Simulation shows ESecRout's performance comparison with the non-secure routing protocol AODV [1] and the secure routing protocol SAODV [2]. Our protocol needs a little more route discovery overhead (about 8%) and costs a little more energy (about 8%) than AODV, but it performs much better than SAODV which needs much more route discovery overhead (about 33%) and costs much more energy (35%) than AODV. Simulation results also show that the packet delivery ratio and packet latency of AODV, SAODV, and ESecRout are almost the same. Thus, we show that our protocol ESecRout provides energy efficient secure routing.