The case-history of a quay wall which went on the verge of collapse and was subsequently stabilised is reported in the paper. The main instability cause was the deepening of sea floor in front of the wall. Stabilising measures were selected taking into account the extreme sensitivity of the structure even to modest mechanical actions such those induced by construction equipment. They were implemented in successive stages specifically designed for avoiding critical stability situations. Frequent displacement measurements during work execution showed temporary marked increases of the rate of displacement. The stabilisation works were successfully completed and the quay was brought back into operation.