The increasing use of capillary electrophoresis (CE) in all areas of analytical chemistry has been reflected in the appearance since 1990 of significant numbers of fundamental studies and applications of CE in the area of separations of metal ions. In this article all aspects of separations of metal ions by CE are reviewed and discussed, including general concepts and approaches, sample introduction, complex formation and sample stacking, separation selectivity, the role of kinetics, capillary wall chemistry, detection techniques, method validation, and applications to metal determinations in various matrices.