Review of 2,700 abdominal ultrasonic examinations revealed 56 patients whose kidneys showed increased echogenicity. Echogenic kidneys were associated with medical renal disease in 94% of cases (30% glomerular, 48% tubulointerstitial, 16% end-stage) and with no detectable renal disease in 6% (three patients). Patterns of increased echogenicity and renal size were evaluated. Specific patterns occurred in end-stage renal disease and polycystic kidney disease. Other medical renal diseases had overlapping ultrasonographic features. Some generalizations could be made although increased echogenicity was often nonspecific.