1. We present in this review a general description of marine protected areas (MPAs) in the northwestern Mediterranean and some general principles for the establishment of protected areas, including their size, location, biotope composition, regulation, and management.2. Many Mediterranean MPAs are located around or adjacent to islands, but the placement ofa marine reserve close to a large urban area is not necessarily a handicap, as has been demonstrated by some examples. It is not, therefore, necessary to restrict future MPAs solely to regions of low human density.3. The conceptual question of MPA size (single large or several small SLOSS debate) has never been explicitly considered in the selection of Mediterranenan MPAs. However, studies of fish recruitment in MPAs, and the development of a network of small MPAs between Spain and France have highlighted the importance and value of small sized MPAs (200-2000 ha).4. Whatever the location of a future MPA, its success as measured in terms of stock restoration will depend on whether (i) sufficient suitable habitat is available, (ii) the variety and abundance of prey species are adequate and (iii) the possibilities for recruitment of the biota are reasonable.5. The initial choices of zonation and legislation regulating the management of any future MPA are of primary importance. The zonation plan should be as simple as possible (gradation of 2 or 3 levels) and it should be acknowledged that the significance of management conflicts within a MPA will be inversely proportional to the extent of preliminary consultations with all of the users, both professional and amateur.6. The examples of semi-protected areas where professional fishing is still allowed demonstrate without ambiguity the negative impact of spear fishing, and the limited impacts from regulated professional activities on fish assemblages. The means of regulating consist essentially of (i) a prohibition of certain type of fishing methods (trawling); and (ii) a limitation of the numbers of fishermen by a system of restriction or authorization.7. In the MPAs examined, there is a great diversity of situations in relation to the size of and distribution of duties between staff assigned to their management. However, the single most important factor underlying whether or not a MPA will be successful and beneficial is the presenceof a dedicated staff.