For more than 50 years now, nuclear medicine has offered therapeutic procedures in oncology. These comprise bone pain palliation in bone metastases of prostate and breast cancer. For more than 20 years now, metaiodobenzylguanidine (mlBG) has been used to treat neuroendocrine tumors. Ten years ago, somatostatin analogues such as Y-90 Dotatoc became available for the treatment of somatostatin receptor-positive tumors. The intracavitary injection of radiocolloids has been well known for 5 decades now and can be used in malignant effusions. Invasive procedures such as intra-arterial injection of I-131 lipiodol may be applied in multifocal, nonresectable hepatocellular carcinoma. Beyond that, intratumoral injection of radioisotopes may be used in cutaneous metastases. Radioimmunotherapy using labeled tumor antibodies is now also available, especially in patients with non-Hodgkin's lymphoma.