Sixteen patients with adult polycystic kidney disease (PKD) were studied by gray scale B mode ultrasonography. The nephrosonographic appearance of adult PKD is a spectrum ranging from kidneys of normal size to enlarged kidneys with multiple variable-sized cysts. Strong focal cortical echoes were present in patients with only small cysts in the renal cortex. Hepatic cysts, which appeared as sharply marginated anechoic regions within the liver parenchyma, were detected by ultrasound in 50% of our patients. Hepatic and renal cysts appeared on computed tomograms as sharply defined, ovoid areas of low attenuation. There was good diagnostic correlation between ultrasonography and computed tomograms as sharply defined, ovoid areas of low attenuation. There was good diagnostic correlation between ultrasonography and computed tomography. Ultrasound and computed tomography are accurate methods for diagnosis of adult PKD; however, the ability to diagnose quickly and noninvasively both renal involvement and associated extrarenal involvement makes ultrasound the procedure of choice for diagnosis, screening, and followup.