Abstract. - The subject hereunder discussed creates the possibility to debate of two different opinions dealing with the influence of ports and harbours in the urban and regional organisation. The introduction shows that ports and towns have to be studied separately : it is the only way to analyse the special links established between them. The question is : how and how much these links have the opportunity to interfere with the townscape, with urban centrality and zones of influence, and so with the urban framework ? 1 . Ports and the townscape. In the view of J.P. DAMAIS, ports and towns have formerly penetrated each other strongly ; but modifications happen with the arriving of industry, in the XIXth century ; then the port created a large employement and the town was taking its life upon it, and governed it. But in the XXth century, port economy separates from urban one ; maritime traffics change in their nature and width ; port and town organisations are now too different to coincide. Formerly, it was possible to speak of «city port» ; now it is necessary to speak of «town and port». 2. Ports and urban development : the Hong Kong and Singapour case study. Chr. VERLAQUE describes the surprising growth of these two city ports created from the great maritime trade ; this trade led to a financial power and to the possession of large merchant fleets ; then, immigration from South East Asia obliged to expand some light industries ; the ports were interested yet in this development. The growth of port equipments and of the two towns leads to a combined organisation and planning ; new towns are created together with new maritime areas. In both case, a transformation from a strictly maritime activity to a more diversified economy is shown ; however, ports remain the most important wealth. 3. Cityport development and regional organisation of space : the Lower Seine case study. For Fr. GAY, port functions have a specific impact on regional organisation of space, especially - as in the case of the Lower Seine - when two important cityports are in competition. Regional coordination can be seen in new perspectives in the light of the growing influence of big state corporations and multinational firms. On a lower scale the estuary tends to be unified through port development and new large scale bridges as in Humberside. A new emphasis must be paid to the way ports are organizing their regions through the specific conditions of their labour areas in modern MIDAS. Consequences on regional planning and limits of regions are examined in conclusion. 4. The influence of ports in urban and regional organisation : weakness ? or strength ? Here is the debate. According to J.C. BOYER, seaports took a prominent part in regional life and economy, but nowaday they appear more and more as the tools of a national and international relation system. Ports seem to be more the tools for a national and international economy than for regional life. Their influence are spreading largely but in a discontinued way and without regular and permanent contacts with regional space. - On the contrary, A. VIGARIÉ shows that city ports keep a powerful influence on the space organisation on townscape and urban framework. The port gives to the town men and wealth, and so it gives a large help to the urban regional influence. Hinterland and foreland, two special subjects in port methodology, can prove that port activities art extensive links in which urban structures are intricately mixed up.