A rare association of embryonal genitourinary tumor(s) with cerebral malformations has been reported in eight infants with variegated mosaic aneuploidy (VMA) and premature centromere division. The authors report a new case of cystic partially differentiated nephroblastoma and embryonal rhabdomyosarcoma associated with VMA, premature centromere division, microcephalus, Dandy-Walker malformation, and cataracts. Nonrandom involvement of the chromosomes was found in VMA of the lymphocytes and the skin fibroblasts. In the cultured nephroblastoma cells, hyperdiploidy involving the same group of chromosomes involved in VMA of the somatic cells was observed, suggesting their derivation from the aneuploid population of the somatic cells.