Cystic nephroma is an uncommon lesion, whose etiology and pathogenesis is still debated: some Authors designate it as being of neoplastic origin, other ones of dysplastic or hamartomous origin. Also epidemiology makes difficult its pathogenetic interpretation, as being especially affected children under age of fourth year and adults within the 5th and 6th decade. The Authors report two cases of cystic nephroma examined in two female patients 30 and 74 aged. The most interesting matters are: 1) Possibility of a pre-operative diagnosis of founded suspicion, based on pathologic criteria, codified in literature (unilateral and multilocular cyst which doesn't communicate with the renal collecting system, separated by delicate septae without mature renal tissue) and on respective ultrasonographic, CT and angiographic patterns; 2) Possibility of programming a surgical-conservative strategy; 3) Knowledge about possibility of foci association of adeno-carcinoma or nephroblastoma in the lesion, that, nevertheless, if not widespread, it should not modified neither therapeutical proceeding nor prognosis, generally favourable.