The use of wireless networks has spread further than simple data transfer to delay sensitive and loss tolerant multimedia applications. The IEEE 802.11 WLAN has become a dominating technology due to its low cost and ease of implementation. This paper presents a cross-layer mapping algorithm to improve the quality of transmission of H. 264 (a recently-developed video coding standard of the ITU-T Video Coding Experts Group) video stream over IEEE 802.11e-based wireless networks. The major goals of H 264 standard have focused on improving the rate distortion process and enhanced compression performance. Our proposed cross-layer design involves the mapping of H. 264 video slices (packets) to appropriate access categories of IEEE 802.11e according to their significance information. We evaluate the performance of our proposed cross-layer design and the results obtained demonstrate its effectiveness in exploiting characteristics of the MAC and application layers to improve the video transmission quality.