**Abstract**

Radiopharmaceuticals are radioactive compounds which have a bound radionuclide in their structure. It is used to direct the radionuclide to a location to be treated or to obtain images. Nuclear medicine is the science that in the charge of employing radiopharmaceuticals, which is very useful support for medicine assisting in several diagnoses and treatments for cancer. The main aim of this work is to shed lights on the main radionuclides and metal complexes which are used as radiopharmaceuticals. Radiopharmaceuticals are compounds of technetium (99mTc) is considered as the main metal complexes like sodium pertechnetate and methylenediphosphonate MDP99mTc and other compounds which used in nuclear medicine for diagnosis such as: (1) indium (111In); (2) thallium (201Tl); (3) gallium (67Ga, 68Ga); (4) iodine (123I and 131I); (5) chromium (51Cr); (6) sulfur (35S); (7) phosphorus (32P); (8) a18F. They are very important in the early diagnosis for several diseases such as cancer, kidney, cardiovascular, liver. Generally, technetium compounds are main radiopharmaceuticals, widely all over the word.

**Keywords:** therapy or diagnostic, radionuclide, compounds, stability, abnormal distribution, radionuclide reactor, a radioactive- reactor, therapeutic radiopharmaceutical precursor, technetium, radioisotopes-
