An adaptive routing algorithm for packet-switched networks is proposed. This algorithm updates both the estimate of external traffic input and the routing assignments at each iteration. The routing assignments determine the proportions of the traffic destined for node

to be sent from node

through the outgoing links of

. The algorithm maintains the loop freedom of the routing assignment at each iteration. It also achieves the minimum delay of the network as the limit of its successive updating procedure. The additional features of the algorithm are that it allows at any iteration some routing assignments which theoretically induce infinite delay and that it may utilize variable scaling factors to speed up the convergence.