Neonatal urinomas can be defined as encapsulated extravasations of urine occurring secondary to congenital obstructive uropathies. Since 1978, four patients with proven urinomas have been studied at the Medical University of South Carolina, three of which had posterior urethral valves and the fourth, a segmental ureteral atresia. They were classified into three major types; subcapsular, diffuse perirenal and localized perirenal. The radiologic and imaging appearances are demonstrated. We found the most efficacious approach for identification of neonatal urinomas to be renal ultrasound, voiding cystourethrography and the Tc-99m DPTA renal scintigraphy.