The quality of multimedia' applications depends primarily on how the different media are compressed, packetised, and transported over a network. Compression algorithms reduce the amount of data to be transmitted by removing redundancy in the media. Most of these algorithms are lossy, and can significantly degrade the media quality. Furt~ermore, degradations occur when packets are transported over lossy and unreliable networks such as the Internet. Due to the heterogeneous nature of multimedia traffic, complex interactions occur when they are transported over the same medium. This is true in packetswitched networks such as the Internet, where packet delivery is not guaranteed. Each traffic requires different treatment from the network transport services, which can have direct impact on other traffic.This thesis presents an evaluation of how multimedia traffic affect one another when transported over the same medium, for various network conditions. Evaluation is performed using video, audio and still images over a synthesised platform/system developed for this purpose. A traffic generator, which generates traffic from real video sequences, has also been developed. The platform and the traffic generator serve as a novel tool for simulating any number and type of traffic, for evaluation of multimedia traffic interactions.