Abstract: A method of controlling congestion in a node of an asynchronous transmission system in which cells forming packets are transmitted, wherein cells are accepted or rejected according to the peak cell rate (PCR) of the connection on which the cells are transmitted, and the peak cell rate is evaluated based on peak cell rate information negotiated with the system for the connection. When the first cell of a packet arrives, the evaluated peak cell rate of the cells of the packet and the remaining transmission capacity (RTC) at the node are compared, the latter being calculated as the difference between the possible cell rate of the node and the sum of the cell rates of the connections of the packets in process of transmission via the node. The method provides a simple way of effectively controlling congestion without having to transmit resource management information in dedicated cells.