Multilocular cystic nephroma (MCN) is a benign renal lesion believed to be unilateral and nonfamilial. We present 2 cases of MCN in 2 brothers. The older brother had a 10-cm MCN and required radical nephrectomy, and the younger brother had bilateral lesions (6 cm and 3 cm) for which nephron-sparing surgery was possible. Both children underwent chest computed tomography to rule out pleuropulmonary blastoma. These cases suggest a genetic link to the pathogenesis of this lesion is possible and that although MCN can involve the collecting system, it can still be treated with partial nephrectomy.