Time-lapse microcinematography of the cultures of mouse neuroblastoma C-1300 revealed several cases of directional translocation of nucleus-containing cell body along the elongated cytoplasmic processes of differentiated neuron-like cells. This unusual type of intracellular movement observed in vitro is similar to perikaryal translocation previously described in certain types of developing brain neurons in vivo. Translocation of nuclei was often accompanied by local contractions of surrounding cytoplasm. Repeated contractions and relaxations of cytoplasm were also observed in the same cultures in the course of transformation of undifferentiated well-spread neuroblast-like into differentiated neuron-like cells. Possible mechanisms of perikaryal translocations are discussed.