Abstract: The clinical role of ¹⁸F-fluorodeoxyglucose ¹⁸F-FDG PET in renal malignant tumor is mainly for diagnosis of primary or recurrent renal tumors and staging and detection of unsuspected metastases. The impact of ¹⁸F-FDG PET on disease management is due to the findings and confirmed of metastases, which is superior to conventional imagings, eg. CT. But the sensitivity of ¹⁸F-FDG PET in the detection of renal cell carcinoma is lower than CT, it may be in connection with the grade or some property of tumor.