PURPOSE: To evaluate imaging characteristics of metastatic renal tumors in CT and US. MATERIALS AND METHODS: Renal metastases were diagnosed in 25 patients by surgery (n=2), US-guided biopsy (n=15), or follow-up CT (n=8). The primary tumors metastasized to kidney were lung cancer (n=11), adenold cystic carcinoma (n=3), stomach cancer (n=2), and choriocarcinoma (n=2). Twelve cases invloved one kidney and 13 invloved both kidneys. CT was performed in all 25 patients while US was done in 14. We analysed CT findings in respect to number, size, shape, exophytic degree, margin, and degree and homogeneity of the contrast enhancement of the lesion; US findings in regand to echogenicity and homogeneity of the lesion. RESULTS: The average number of the lesions per patient seen on CT was three;average diameter of the lesion was 3.6cm; and 75% (57/76) of all tumors had exophytic degree of 0%. The characteristic CT findings of metastatic renal tumors were round shape (52/76), ill-defined margin (54/76), and poor (76/76) and inhomogeneous (45/76) contrast enhancement. The echogenicity of the tumors were homogeneous (11/18) and isoechoic (10/18) on US. CONCLUSION: Metastatic renal tumors had a tendency of multiple, small, ill-marginated, and less-exophytic nature on CT, and homogeneous, isoechoic appearance on US. The familiarity with the constellation of CT and US findings of renal metastasis described may be helpful in making a correct diagnosis.