In this paper, a simulation tool is presented, suitable for evaluating the performance of the 802.11 e contention-based access. 802.11 e is a very recent amendment to the IEEE 802.11 standard, describing the MAC layer enhancements required for Quality of Service (QoS) provision. Aim of the developed simulator is to provide an accurate and efficient tool for evaluating significant parameters of the 802.11 e protocol, mainly in terms of traffic differentiation for QoS support. To evaluate the accuracy and demonstrate the use of the simulation tool, a number of simulations are performed, following the basic 802.11 e interoperability test procedures.