Wireless networks played a major role and an active research area in the recent years specially the IEEE 802.11 Medium Access Control Protocol (MAC). Due to several limitations of wireless network, this paper aims to improve the performance of Quality of Service (QoS) parameters of the wireless networks by adjusting the Distributed Inter Frame Space (DIFS) value. Several scenarios were carried out using NS2 simulation package to study the impact of this parameter on the overall network performance. The obtained results revealed that carefully adjusting of this parameter significant improvements shall be obtained. © 2011 Praise Worthy Prize S.r.l.-All rights reserved.