ALTHOUGH much has been written on "polycystic kidneys," it cannot be said that the terminology and the classification has definitely been settled. However, with the adoption of this term for every case exhibiting multiple primary congenital cysts in the substance of one or both kidneys, the following major varieties of polycystic kidneys can be distinguished:1-7Polycystic Kidneys of Infantile Type.—In this well-defined group, multiple and very small cysts which are densely packed together replace the whole renal parenchyma of both kidneys almost completely; the kidneys are greatly enlarged; polycystic disease in other organs such as the liver, the pancreas, and the lungs almost constantly coexists; and patients die within the first few days of postnatal life.Polycystic Kidneys of Adult Type.—In this group, many cysts which are larger than those seen in the infantile variety are present, usually in both kidneys however, leaving a little or