The chemical modification of oligomers such as DNA, PNA, MORF, LNA to attach radionuclides for nuclear imaging and radiotherapy applications has become a field rich in innovation as older methods are improved and new methods are introduced. This review intends to provide a brief overview of several chelators currently in use for the labeling of oligomers with metallic radionuclides such as 99m
In and 188
Re. While DNA and its analogs have been radiolabeled with important radionuclides of nonmetals such as 32
F and 125
I, the labeling methods for these isotopes involve covalent chemistry that is quite distinct from the coordinate-covalent chelation chemistry described herein. In this review, we provide a summary of the several chelators that have been covalently conjugated to oligomers for the purpose of radiolabeling with metallic radionuclides by chelation and including details on the conjugation, the choice of radionuclides and labeling methods.