Recent trends in port development show that ports are making increasing efforts to forge mutually beneficial cooperation strategies, particularly ports sharing a common hinterland. In this paper, we analyse the North Adriatic ports (Koper, Rijeka, Trieste and Venice) with a focus on two related themes. First, the complementarity of the North Adriatic (NA) ports in the container market is analysed based on port vessel service patterns and shipping line interviews. We operationalize the analysis of complementarity with an analysis of the effects of multiple port calls on the revenue required to make a call in a specific NA port economically feasible. We conclude that the inclusion of another NA port reduces the minimum required revenue for a call in an additional NA port.Second, we assess the scope and depth of cooperation between ports. We map current and potential future cooperation using a 'cooperation matrix' with two dimensions: the involvement of stakeholders (limited vs. broad), and the depth of cooperation (pre-competitive vs. commercial). We use in-depth interviews with port authorities, terminal operators, rail operators, major shipping lines and forwarders in the NA region to position the NA ports in the matrix. We conclude by discussing prospects of future NAPA ports cooperation.