End-to-End (E2E) flow monitoring is useful for observing performance of networks such as throughput, loss rate, and jitter. Typically, E2E flow monitoring is carried out at end hosts with known tools such as iperf. However, in a large-scale network, the end-host approach for performance measurement may not be easily deployed because of expensive costs and high administrative overheads. Therefore, in this paper, we propose a new E2E flow monitoring method based on IP Flow Information eXport (IPFIX) that could provide QoS metrics such as throughput, retransmission rate, delay, and jitter for TCP/RTP flows. Especially, we present and evaluate a QoS monitoring scheme for RTP flows using SIP. We have extended the IPFIX templates for carrying QoS-related fields, and developed the E2E flow monitoring function with the open source that could be embedded into routers. From experiments, it was shown that the performance of TCP and RTP flows could be easily examined with the IPFIX-based approach....