Knowledge of the manifestation, physiology and the natural course of pediatric upper urinary tract dilatation has grown with the ongoing discussion on adequate imaging. Furthermore, MR-urography techniques (MRU) have matured and have become applicable to infants and children. Modern MRU offers not only increased spatial and temporal resolution, thus enabling an investigation throughout the entire childhood, but also provides (semi-)quantitative functional information on renal perfusion, excretion and drainage. Thus MRU is increasingly considered the ideal non-ionizing "one stop shop" for the assessment of significant upper urinary tract dilatation in children. The goal of this review is to briefly comment on MRU techniques as applicable in childhood, discuss MRU indications, and summarize their potential in children with upper urinary tract dilatation. Additionally, diagnostic imaging algorithms for typical clinical conditions and queries that try to define the role MRU in pediatric upper urinary tract dilatation are suggested and discussed.