The Mediterranean States adopted an action plan for the protection of their common sea from pollution as early as 1975. This comprehensive action plan is not limited to monitoring of marine pollution but includes all aspects relevant to environment and development. It is coordinated from the Athens-based Centre but regional offices also exist being responsible for the implementation of specific programmes. The scientific and technical component of the action plan (the MED POL programme) was the first one to be initiated involving more than 100 Mediterranean research and monitoring institutions. Selected results of the monitoring programme are presented shortly. The following parameters are dealt with: mercury, cadmium, copper and zinc, organohalogen compounds, organotins, organophosphorus compounds, herbicides and fungicides as well as synthetic persistent materials. The results have shown that pollution in the Mediterranean sea is limited to coastal areas where the sources, such as industries and population centres, are found. The north-western Mediterranean has shown higher pollutant concentrations either because of natural sources (case of mercury) or because of the industrial development of the region.