The clinical finding of a case of bilateral pelvic renal ectopia, incidentally discovered in a 31 year-old female, leads us to revise the current theories explaining simple renal ectopia. The pathogenesis of this anomaly of kidney position and rotation is far from being clearly understood. However, in the light of normal process of kidney ascension, we understand this entity can be regarded as an example of time-dependent developmental disorder taking place between the 6th and 9th weeks of human embryogenesis.