Method for transmitting high-priority packets in an IP transmission network based upon the Internet Protocol (IP) wherein low-priority packets or fragments of packets are transmitted between a sender and a receiver and at least a high-priority packet can be transmitted from the sender to the receiver by pre-emption of a low-priority packet or a fragment of packet. the method comprises in the sender, the steps of determining whether a low-priority packet or fragment of packet is being transmitted from the sender to the receiver when a high-priority packet has to be transmitted, setting to 1 a reserved bit within the IP header of the high-priority packet used as a pre-emption indicator if a low-priority packet or fragment of packet is currently transmitted, transmitting the high-priority packet with the pre-emption indicator set to 1 from the sender to the receiver, and resuming the transmission of the low-priority packet or fragment of packet at the end of transmission of the high-priority packet.