This review describes radial segregation results from crystal growth experiments in microgravity, together with their corre-sponding theoretical treatments. The paper is structured in terms of the different factors influencing radial segregation during crystal growth, such as: curved growth interfaces, variations in boundary layer thicknesses, weak convection, facets and magnetic fields. In a number of experiments considerably stronger radial segregation occurs in space than is normally observed on earth. The theoretical treatments lead to a sound understanding of all of the results. Possible ways to avoid the problem, such as the application of magnetic fields, are outlined.