Since there have been increasing applications of IEEE 802.11-based broadcast wireless networks, the ability to characterize medium access control (MAC) behavior and performance of mobile stations plays a key role in understanding and designing such broadcast systems. In this paper, we study the saturation performance of the broadcast scheme in IEEE 802.11 by an analytical model as well as by simulation. Having investigated the literature and studied the features of the broadcast service, we point out that analytical models for saturation performance evaluation of IEEE 802.11 unicast communication cannot simply be reduced for the analysis of broadcast service. Under realistic assumptions, we construct an accurate model to characterize the operation of the backoff counter for broadcast service. Based on solutions to the model, closed-form expressions of broadcast saturation performance indices, including throughput, packet delay, and packet delivery ratio (PDR), are derived. The proposed analytical model is validated by simulation. From the analysis of the proposed model, some observations and constructive suggestions to improve the performance of the broadcast service are given. Numerical results also reveal the characteristics of the broadcast service.