A family is reported with ganglioneuromas in the mother and neuroblastomas in her two daughters co-existing with cases of von Recklinghausen's neurofibromatosis, Hirschsprung's agangliosis, and the jaw-winking syndrome in other family members. There were no detectable constitutional chromosomal defects in the family even when high resolution techniques were applied. Similarly, DNA-hybridization analysis did not reveal gross molecular rearrangements in the vicinity of the proto-oncogenes N-myc-, c-myc, neu, and N-ras. However, the aggregation of several rare, autosomal dominant diseases affecting tissue derived from the neural crest not only suggest a link between te pathogenesis of these disease, but also makes it highly likely that a single mutation segregating within the family is responsible for this association.