Non-enzymatic reagents that efficiently promote the hydrolytic cleavage of DNA currently receive much attention since they have many potential applications in molecular biology. This review focuses on recent progress in the hydrolysis of the phosphodiester backbone of DNA by metal ions and metal complexes. Pioneering work on the sequence-selective DNA scission by an artificial restriction enzyme? which is prepared by covalent attachment of a cerium(IV) complex to an antisense-deoxyoligonucleotide, is discussed.