UWB WiMedia MAC has been widely used in wireless multimedia networks, but it suffers from inefficient channel utilization. In this paper, we propose a reservation based MAC protocol for multimedia data to increase the channel utilization efficiency. The proposed scheme has two components. First, the protocol lets flows with large amounts of data be reserved early among the nodes. Second, when anode allocates slots, the protocol uses wasted slots. We evaluate the performance of the proposed scheme through simulations that compares channel utilization and drop probability with an existing scheme. The simulation results show that the measured performance metrics are improved.