Polycystic renal disease are congenital disorders, most of which are fatal in the postnatal period. a series of ten cases of polycystic renal disease diagnosed prenatally by ultrasonography is presented. diagnostic criteria of ultrasonography for cystic renal disease are; 1. enlarged kidney (4 cases) 2. echogenic density of kidney (3 cases) 3. 0.4-0.9cm sized multiple cysts wihin the renal cortex (3 cases) 4. decreased amount of amniotic fluid (4 cases) 5. hydronephrosis (4 cases) 6. distended bladder (2 cases) 7. absence of bladder (2 cases) Eight of ten cases were confirmed by autopsy. seven cases had other associated congenital anomalies, I. e. pulmonary hypoplasia (5), hepatic fibrosis (3), congenital heart disease (3). tracheoesophageal fistula with imperforate anus (1), caudal regression syndrome (1), Meckel-Gruber syndrome (1) and ambiguous genitalia (2). additional cytogenetic study of the fetus and the careful family history taking followed by prenatal diagnosis of cy tic renal disease. Precise prenatal diagnosis may allow patients the option of elective abortion or may prevent unnecessary obstetric intervention.