Cystic nephroma is a rare and benign renal tumour of unknown origin, usually diagnosed in the first years of childhood or during adult life. To our knowledge, there are no records in the literature of this particular tumour being descried prenatally. We present a case of a fetus diagnosed with cystic nephroma on 16 weeks of gestation. The renal tumour was evaluated by prenatal ultrasound, post mortem with 7T magnetic resonance imaging, and conventional autopsy.