Neuroendocrine tumors (NETs) consist of a heterogeneous group of tumors that are able to uptake neuroamine and/or specific receptors, such as somatostatin receptors, which can play important roles of the localization and treatment of these tumors. When considering therapy with radionuclides, the best radioligand should be carefully investigated. 131I-MIBG and beta-particle emitter labeled somatostatin analogs are well established radionuclide therapy modalities for NETs. 111In, 90Y and 177Lu radiolabeled somatostatin analogues have been used for treatment of NETs. Further, radionuclide therapy modalities, for example, radioimmunotherapy, radiolabeled peptides such as minigastrin are currently under development and in different phases of clinical investigation. For all radionuclides used for therapy, long-term and survival statistics are not yet available and only partial tumour responses have been obtained using 131I-MIBG and 111In-octreotide. Experimental results using 90Y-DOTA-lanreotide as well as 90Y-DOTA-D-Phe1-Tyr3-octreotide and/or 177Lu-DOTA-Tyr3-octreotate have indicated the possible clinical potential of radionuclides receptor-targeted radiotherapy. It may be hoped that the efficacy of radionuclide therapy will be improved by co-administration of chemotherapeutic drugs whose antitumoral properties may be synergistic with that of irradiation.