/sup 67/Ga citrate is most often used in the diagnosis of lung cancer. As judged from reported cases, the accuracy rate was 90%, with a false negative rate being about 5%. Lung ventilation and blood flow scintigraphy are valuable in assessing the degree of damage to lung function and the therapeutic effect rather than in finding lung cancer. In aerosol scintigraphy, sup(99m)Tc labelled aerosols with different particle size depending on the purpose of diagnosis are used; the large particles deposit at the center of the trachea and small size aerosols on the periphery. Aerosol-inhaled scintigraphy is highly valuable for the diagnosis of hilus lung cancer. sup(99m)Tc methylene diphosphate is used in bone scintigraphy to detect bone metastasis. But it sometimes gives false positive results such as in the case of senile bone changes. Another valuable method of diagnosis is emission CT by which various substances having affinity for the tumor can be detected by labelling them with a proton emitting nuclear species such as 11 C, /sup 13/N, /sup 15/O and /sup 18/F. Some cases of lung cancer, and the radionuclide methods used in the diagnosis are shown.