The paper deals with the mutual relation of the nucleole in sex differentiation in various sex forms of hemp (Cannabis sativaL.). The genotype divergencies of the different sex forms are expressed in the size of the nucleoles both in pollen mother cells as also in the nucleoles of young pollen grains. Results of the measurement were statistically evaluated by means of the t- test and analysis of variation. The fact that the difference in genotype is more evident in the size of the nucleoles (the differences are statistically significant) than in the size of the cell nuclei seems to prove that the nucleole in all probablity has a certain influence on the sex differentiation.