The light and electron microscopic cytology of nuclear division in Vaucheria litorea Hofman ex C. Agardh is described. The interphase nucleus contains a prominent nucleolus and is associated with lipid droplets. The nucleus migrates through the coenocytic filament during all phases of division. During early prophase, the centrioles migrate to each pole, and the nucleolus fragments. At metaphase, the intra-nuclear spindles, which consist of continuous and chromosomal microtubules, are enclosed by a fully intact nuclear envelope. The nuclear membrane persists throughout the division. Chromosome separation is accomplished by lengthening of continuous microtubules at anaphase. Considerable elongation of continuous microtubules produces an extremely long interzonal spindle between the daughter nuclei which is ultimately separated at telophase by the invagination of the inner nuclear membrane and an electrondense area just within the abscission zone. Comparisons are made between Vaucheria and other organisms with a similar mitotic division.