The review presented here lays out the present state of the art in the field of radionuclide therapies specifically targeted against the nucleus of cancer cells, focussing on the use of Auger-electron-emitters. Nuclear localisation of radionuclides increases DNA damage and cell kill, and, in the case of Auger-electron therapy, is deemed necessary for therapeutic effect. Several strategies will be discussed to direct radionuclides to the nucleoplasm, even to specific protein targets within the nucleus. An overview is given of the applications of Auger-electron-emitting radionuclide therapy targeting the nucleus. Finally, a few suggestions are made as how radioimmunotherapy with nuclear targets can be improved, and the challenges that might be met, such as how to perform accurate dosimetry measurements, are examined.