Neuroblastoma cells exhibit a wide variety of patterns of neurite morphology. However, when these cells are induced to extend neurites under conditions in which mitotic sister cells are readily identifiable, 60% of these sister pairs display analogous morphologies. These cells are related either as identical twins or as mirror images of each other. The relatedness is expressed in considerable detail of neurite morphology. These relationshiops can persist through at least two cell divisions. The results suggest that animal cells can inherit specific determinants of shape.