This paper provides a history of the development of regional geochemical mapping. Modern geochemistry was born in the Soviet Union in the 1930s, and the basic methodologies for regional mapping had been developed by the late 1960s, with important extensions being made in the 1980s. The paper records the development of regional geochemical surveys, or mapping, in the context of spatial scale and transition from a mineral exploration and resource assessment tool to an environmental mapping exercise supporting multi-disciplinary research. Attention is drawn to the role of the International Geological Correlation Program's Projects 259 and 360, and the continuing role of the International Union of Geological Sciences, in providing an international focus and dimension to global geochemical mapping. The paper closes with a section on some of the current research issues, opportunities and challenges for regional geochemical mapping.