The results of angiography and sonography in 132 patients suspected of having a space-occuping lesion in a kidney were compared; they were examined by excretion urography, ultrasound and renal angiography. All lesions demonstrated angiographically had already been seen by ultrasound. Difficulties were experienced with cysts of less than 3 cm. Diameter situated in the region of the hilum, which did not always produce echo-free images. Infected renal cysts appeared as avascular space-occupying lesions on angiography, but showed echoes on sonography.