Abstract: Objective To evaluate the value of whole body ¹⁸F-FDG PET（PET/CT） for space occupying renal cancer. Methods Characteristics of whole-body ¹⁸F-FDG PET imaging for 78 patients with space occupying solid renal cancer were analyzed,which showed space occupying solid renal lesions in 28,41,9 patients,respectively.Fifty minutes after injection with ¹⁸F-FDG PET（5.55MBq/kg）,Ecat exact HR or GE discovery VCT was used to collect the 3-dimensional images.ROI was set at the renal foci observed.SUV_max≥2.5 was judged as positive PET（malignant） and SUV_max＜2.5 was judged as negative PET（benign）.The disease was diagnosed following the CT and fusion images in PET/CT. Results Pathological examination showed renal cancer and positive PET in 21 and 11 patients,respectively.Of the 7 patients with benign lesions,5 were found to be hamartoma and 1 was found to have cyst which was positive for PET.Of the 11 patients who were found to have renal cancer by ¹⁸F-FDG PET/CT,5 were positive for PET.Of the 13 patients with metastasis or relapse after operation,10 were positive for PET. Conclusion ¹⁸F-FDG PET has a limited value for the diagnosis of primary renal cancer but has a rather high value for the diagnosis of metastasis or relapse of renal cancer after operation.