Motivated by the promising voice over IP technology and the wide service availability of WLANs, the application of voice over WLAN (VoWLAN) is expected to experience dramatic growth in the near future. Originally designed for high-rate data traffic, WLANs may experience bandwidth inefficiency when supporting delay-sensitive and low-rate voice traffic. This article proposes mechanisms to enhance QoS support capability of IEEE 802.11e for voice service. Unnecessary polling of silent voice stations is avoided, and header and control overheads are suppressed significantly. Compared to IEEE 802.11e, our mechanisms can greatly improve the capacity of WLANs to support voice service.