The Mediterranean Atmospheric Mercury Cycle System (MAMCS) project was performed between 1998 and 2000 and involved the collaboration of universities and research institutes from Europe, Israel and Turkey. The main goal of MAMCS was to investigate dynamic processes affecting the cycle of mercury in the Mediterranean atmosphere by combining ad hoc field measurements and modelling tasks. To study the fate of Hg in the Mediterranean Basin an updated emission inventory was compiled for Europe and the countries bordering the Mediterranean Sea. Models were developed to describe the individual atmospheric processes which influence the chemical and physical characteristics of atmospheric Hg, and these were coupled to meteorological models to examine the dispersion and deposition of Hg species in the Mediterranean Basin. One intercomparison and four two-week measurement campaigns were carried out over a three-year period. The work presented here describes the results in general terms but focuses on the areas where definite conclusions were unforthcoming and thus highlights those aspects where, in spite of advances made in the understanding of Hg cycling, further work is necessary in order to be able to predict confidently Hg and Hg compound concentration fields and deposition patterns.