Packet buffers in routers play a major role in congestion control in existing Internet. They compensate for the incoming traffic bursts transmitted by aggressive TCP applications. The appropriate sizing of buffers is important for providing equilibrium between the high link utilization, the loss ratio and the queueing delay. There is a growing need for routers with small buffers in high speed networks. In this paper we investigate the performance of active queue management algorithms with very small buffers. In particular, we show, that the use of very small buffers does not influence throughput on bottlenecked links if mixed (TCP / UDP) traffic is involved. On the other hand a very small buffer may lead to degradation of the inter-flow fairness.