Kidney cysts are quite common in adults. Though small simple renal cysts in an adult over 30-40 years of age are not too unusual, however, if the same cysts are seen in a child, and especially if there are additional findings, then several diagnostic possibilities may come to mind. The role of ultrasound, together with the help of intravenous contrast agents and Doppler mode, is very critical in describing the morphologic features and follow-up of the complex or multiple and bilateral renal cysts. Sonographic signs are occasionally specific for diagnosis, but in many cases they should be evaluated together with the other genetic and clinical data to reach a diagnosis.The first part of this pictorial essay includes "non-genetic cystic renal diseases" and the second part will include "genetic cystic renal diseases".