In this paper, a dual band planar inverted F antenna (PIFA) is designed for wireless communication intended to be used in wireless body sensor networks. The designed PIFA operates at two different frequency bands, 2.45 GHz (ISM band) and 5.2 GHz (HiperLAN band). In body-centric wireless networks antennas need to be integrated with wireless wearable sensors. An antenna is an essential part of wearable body sensor networks. For on-body communications antennas need to be less sensitive from human body effects. For body-centric communications wearable devices need to communicate with the devices located over the surface and also there is a need of communication from on-body devices to off-body units. Based on this need a dual band planar inverted F antenna is designed which works at two different frequency bands, i.e., 2.45 GHz and 5.2 GHz. The 2.45 GHz is proposed for establishing communication among the wireless sensor devices attached on the human body while 5.2 GHz is proposed for the communications form on-body to off-body devices. The proposed antenna is very compact and due to having ground plane at the backside it shows less sensitive to the effects of the human body tissues. Computer Simulation Technology (CST) microwave studio™ was used for antenna design and simulation purposes. Performance parameters such as return loss, bandwidth, radiation pattern and efficiency of this antenna are shown and investigated. These performance parameters of the proposed antenna have been investigated at free space and close proximity to the human body. Simulation results and analysis show that the performance parameters of the proposed very good results at both frequency bands. Due to its compact size, less sensitive to the human body tissues and dual band functionality, it will be a good candidate for wireless wearable body sensor networks.