Hydronephrosis, "distension in varying degrees of pelvis and calyces, accompanied by progressive atrophy of renal parenchyma due to obstruction in urinary flow", is an apparently simple reno-urinary disease, but, in reality, by association of its own characters with those conferred by causative lesions, becomes of a significant complexity. The purpose of this paper is to demonstrate the plurivalent character of this entity on a batch of cases with congenital hydronephrosis, by identification of lesional features correlated with cause of disease. The etiology of hydronephrosis in analyzed cases was characterized by heterogeneity: polar inferior artery, horseshoe kidney, extrarenal pelvis, transverse valves of pelviureteral junction (PUJ), adhesion of ureter to PUJ, intrinsic stenosis of PUJ, vesico-ureteral reflux, posterior urethral valves, stenosis of urethral meatus. The way of intervention of urinary obstruction and the uni- or bilateral character of damage were definitory for the macroscopical appearance of the hydronephrotic kidney, renal pelvis demonstrating its role of expansion room for kidney protection. In analyzed cases of congenital hydronephrosis, correlation specific cause-pelvic lesion evidenced histopathological differences related to etiology. Anatomical preparations obtained by injection followed by corrosion have revealed that renal vessels appear elongated, distanced from each other and even reduced in density, which explains the appearance of ischemia accompanying pathogenetic changes of obstructive uropathy. Regardless of etiology, all cases of congenital hydronephrosis were characterized by varying degrees of fibrosis in chorion of renal pelvis, accompanied by active chronic inflammation, observation that support the idea of connection between the two pathological changes.