The incidental finding of hyalinized glomeruli in otherwise normal infant kidneys is referred to as congenital glomerulosclerosis. Two infants had extensive glomerulosclerosis manifested by nephrotic syndrome, severe oliguria, and progressive renal failure. Both patients were believed to have had intrauterine infections. These two cases have unequivocally identified congenital glomerulosclerosis as one of the causes of nephrotic syndrome in infancy. In addition, they suggest that extensive glomerulosclerosis in some cases may be a result of congenital infections.