Numerous methods have been described for the separation and purification of radionuclides for application in diagnostic and therapeutic nuclear medicine, among them ion exchange, solvent extraction, and various forms of chromatography. Although extraction chromatography has previously been shown to provide a means of performing a number of separations of potential use in radionuclide generator systems, the application of the technique to generator development has thus far been limited. Recent work directed at improved methods for the determination of radionuclides in biological and environmental samples has led to the development of a series of novel extraction chromatographic resins exhibiting enhanced metal ion retention from strongly acidic media and excellent selectivity, among them materials suitable for the isolation of Bi-212, Y-90, and Bi-213. These resins, along with extraction chromatographic materials employing functionalized supports to improve their physical stability or metal ion retention properties, are shown to offer promise in the development of improved radionuclide generators.