The main aim of this paper is to present a pricing mechanism appropriate for allocating common maritime infrastructure cost which would allow not only a fair and efficient allocation, but also, a solution which would take into account demand characteristics assuring a realistic interpretation of market's behaviour. The proposed solution concept is that of the "ratio equilibrium". Its main qualities consist in guaranteeing a balanced budget, and being - from a strategic point of view - a stable solution. In other words, no port user will be discouraged from using the infrastructure by the assignment of a cost-share that is too high. This latter feature adds a competitive element into the calculations and can be considered as an innovative feature of this analysis. A numeric example is presented. (C) 2000 Elsevier Science Ltd. All rights reserved.