For the sake of improving the overhead occurring due to control operations and to attain the reliable data signaling in the patient monitoring system based on ZigBee, we are focusing on the comparative performance evaluation of different routing algorithm in a wireless body area network (WBAN) using the OPNET simulation tool. WBAN contains the number of wireless mobile nodes forming an unpredictable topology and link instability that make routing a core issue. In this paper a comparative study of three routing algorithms named AODV, DSR, and OLSR has been done with increasing number of wireless nodes in WBAN on account of end to end delay, load, and throughput. Simulation results demonstrate that OLSR routing protocol outperforms among all protocols under an increasing number of node scenario. © 2014 IEEE.