Abstract—Wireless sensor networks(WSNs) have been regarded as an incarnation of Ad Hoc Networks for a specific application. Since a WSN consists of potentially hundreds of low cost, small size and battery powered sensor nodes, it has more potentials than a MANET to be depolyed in many emerging areas. But they also raised many new challenges and these challenges include the design of embedded sensors and wireless networking technology, ie. routing protocols and network security. Many ad hoc routing protocols such as AODV, DSR, DSDR, TORA and OLSR, which have been developed particularly for the mobile wireless ad hoc networks(MANETs), performed satisfactorily on MANETs. In this paper, we investigate how well these ad-hoc routing protocols work on wireless sensor networks (WSNs). We focus on their performances in terms of average end-to-end delay, packet delivery ratio and routing overheads.