Biodiversity conservation has become one of today’s major challenges in a complex socio-ecological context, where common socioeconomic needs for resources exploitation are confronted to striking ecological conservation priorities. Protected areas constitute the key foundation for national and international strategies of effective biodiversity and ecosystems conservation. This paper assesses the effectiveness of protected areas networks in representing key ecological assemblages in Mediterranean environments. Based on a spatial interpretation of the distribution of existing and «preset» protected areas in Lebanon, and the analysis of their coherence with key ecological conservation needs, the pertinence of protected areas designation with respect to biodiversity conservation priorities is assessed. Analysis is performed through the overlay of the protected areas map of Lebanon with that of the areas of high ecological conservation value, the land cover/land use map, the soil map, and the overlaid map of bioclimatic and vegetation levels. A chi-square statistic is also used to significantly compare and assess the distribution of existing protected areas according to land cover, soil and bioclimatic/vegetation aspects. Results exhibit that the existing network of protected areas does not represent the country’s main ecological assets in terms of species richness, soil specificities, important areas for biodiversity, and key eco-complexes. Current protected areas designation seems to answer very particular needs and to follow sociopolitical opportunities in Lebanon (in particular) and the Mediterranean (in general), while it should be based on pertinent ecological and socioeconomic criteria that would highlight the relevance and priority for conservation measures. Rethinking/widening the government efforts towards biodiversity protection is thus identified as a major need.