A wireless body area network (WBAN) allows the integration of low power, invasive or non-invasive miniaturized sensors around a human body. Each intelligent sensor has enough capability to analyze and process the physiological parameters and to forward all the information to a central intelligent node for disease management, diagnosis and prescription. The data transmission rate of various biosensors is heterogeneous. Furthermore, the limited energy resources and computational power of these sensors have urged the development of low power energy efficient medium access control (MAC) protocol. This paper studies the performance of Preamble-Based time division multiple access (PB-TDMA) protocol for a heterogeneous non-invasive WBAN. Simulation results show that the performance of PB-TDMA protocol outperforms S-MAC and IEEE 802.11 DCF in terms of throughput and power consumption.