This chapter covers current knowledge of noble gas composition in the Earth's mantle, with particular reference to its heterogeneity. It discusses the evolution of the mantle–atmosphere pair through the study of degassing and regassing of the Earth's mantle. The chapter presents the dynamics of the present and early mantle. It also presents three open questions on the geochemistry of noble gases on Earth. Noble gases in meteorites have been studied since the 1960s, yet there are still uncertainties about the isotopic compositions of all the noble gases in the Earth's parent bodies. Considering the dynamics of the magma ocean, we could suggest that massive degassing may have taken place – although the life span of a magma ocean and its crystallization by the environment may have partially limited complete mantle degassing, thus preserving a primitive reservoir of noble gases in the deep mantle.