In this paper, a secure and adaptive multimedia transmission framework is proposed to maintain the quality of service (QoS) of the multimedia streams during the Denial-of-Service (DoS) attacks. A DoS attack generates a large amount of traffic, which will occupy the bandwidth and degrade the quality of video. The proposed framework consists of two components: intrusion detection and adaptive transmission management. The intrusion detection component monitors the incoming traffic to the server, detects the attacks, and interacts with the adaptive transmission management component; while the adaptive transmission management component is designed to improve QoS of the video via the efficient utilization of the network resources. With the detection of the DoS attacks, the bandwidth occupied by the attacks can be reduced and protected for video transmission. The results of our preliminary simulations in NS2 show that the quality of the multimedia stream can still be maintained during an att...