Urinoma is defined as an encapsulated collection of extravasated urine in the perirenal or paraureteral space. Urinomas in childhood are rare and usually either secondary to obstructive uropathies or due to blunt or penetrating trauma leading to injuries of the collecting system and/or ureter. Spontaneous perinephric urinomas are rare. We report the case of an 8-year-old boy with bilateral spontaneous perinephric urinomas secondary to an abnormally elevated voiding pressure with detrusor sphincter dyssynergia. The available literature on this subject is reviewed, and clinical features, pathophysiology, and treatment of this entity are discussed.