The US and CT findings of renal metastases are described in a series of 26 patients. US findings were round or oval masses ranging in diameter from 1.5 cm to 8 cm (mean: 4.2 cm); in only 21.2% of cases lesion diameters were less than or equal to 3 cm. In most patients (84.8%) the metastatic lesions were hypo-isoechoic, while in the extant cases they were either mildly hyperechoic or inhomogeneous. CT findings were round masses with variable diameters (1 cm to 8 cm; mean: 2.7 cm); in most cases (86.4%) lesions diameters were less than or equal to 3 cm. The latter finding was in significant disagreement with US results. CT densities were within the soft-tissue range, and always hypodense if compared to normal renal parenchyma in contrast-enhanced scans. Few cases of perirenal metastases were observed. US sensitivity was only 57%, much lower than that of CT; the latter method yielded no false negatives. CT showed metastatic lesions in patients with normal US findings; in 2 cases a greater number of lesions was detected with CT than with US. Our results are in substantial agreement with literature data, as far as US and CT findings are concerned; however, a lower incidence of bilateral cases was observed in our series than in previous reports. Our results support the primary role of CT in the detection of renal metastases thanks to its high sensitivity and to its allowing the simultaneous evaluation of other organs.