The 1,2-diamine motif is present in a number of natural products with interesting biological activity and in many important pharmaceutical agents. Chiral 1,2-diamines are also widely used as the control elements in asymmetric synthesis and catalysis. Such compounds are thus an attractive target for the synthetic chemist. Although the diamination of an alkene seems an obvious route to these structures, far less research has been devoted to it than to the analogous dihydroxylation or aminohydroxylation reactions that are well-established processes in asymmetric synthesis. Here, we examine recent advances in metal-catalysed diamination reactions and their asymmetric variants. Given the prevalence of these structures, it seems likely that they will find extensive application in the construction of natural products and drug molecules in the near future.