Real-time multimedia applications use the user datagram protocol (UDP) because of the inherent conservative nature of the congestion avoidance schemes of transmission control protocol (TCP). The effects of such uncontrolled flows on the Internet have not yet been felt because UDP traffic constitutes at most only âˆ¼ 20% of the total Internet traffic. However, it is pertinent that real-time multimedia applications become better citizens of the Internet, while at the same time delivering acceptable quality of service (QoS). Network flow accumulation is proposed for use as the basis for active flow control. Novel end-to-end active flow control schemes are proposed for unicast real-time multimedia applications transmitting over best-effort networks. The performance of the proposed control schemes is evaluated using the ns-2 simulation environment. The research concludes that active control of hard, real-time flows results in the same ormarginally better QoS as no flow control. However, the bandwidth usage of actively controlled flows is significantly lower than that of uncontrolled flows. The scalability of the proposed active control schemes is acceptable. Â© 2009 Springer London.