This article reviews the common pediatric urologic problem of renal du
plication and the variety of anomalies associated with duplication. Sp
ecifically, the embryology, presentation, evaluation, and comments on
management concerning simple duplex systems and those associated with
ureteroceles and ectopic ureters are addressed. In addition, the less
frequently seen but clinically significant problems of renal fusion an
d ectopia are reviewed.