In the Mediterranean basin, man has had close ties with groundwater since prehistoric times, which magnifies the need to investigate and manage this resource in an appropriate way, to plan water use, protect it from pollution and to keep it in good condition for forthcoming generations. Researchers, technicians, managers and politicians who participated in these two international congresses on groundwater in the Mediterranean (AQUAinMED’06, Malaga, Spain in April 2006 and GIRE3D, Marrakech, Morocco in May 2006), have given their support to this Declaration on Groundwater in the Mediterranean. UNESCO’s International Hydrological Programme (IHP) participated in the organization of AQUAinMED’06 and supports the Declaration as a major contribution to understanding groundwater in the Mediterranean context. The Declaration is aimed at the governments of Mediterranean and EU countries, national and international associations and agencies, and companies and local and regional administrations that are concerned with groundwater. The signatories of this Declaration recommend, as a general principle, promoting research, passing new regulations and national legislation to promote integrated groundwater management, and developing educational programmes to raise awareness of groundwater, to protect it and to promote sustainable use of this natural resource in Mediterranean countries.