By the methods of quantitative cytophotometry, we have identified the changes in the nucleus and of some intranuclear compartments in the early stages of infection with encephalomyocarditis virus (EMCV). They can be characterized as early 1 - 2 hours post infection (hpi) and temporary increase (duration about 1 hour) in the content of the acidic proteins of the nucleolus, changing their decline to the control values. Then (after 1 - 2 hours) follows an increase in RNA content of nucleoli to 4 hours post infection (the process takes about 2 hours). The increase in RNA content in nucleoli is in approximately the same time (slightly behind) with the activation of PML bodies (2 - 4 hpi). Then, the RNA content in nucleoli decreased to the control values, while simultaneously decreasing activity of PML bodies (ranging from 5 - 6 hpi). The early stages of infection EMCV are also characterized by the tendency to increase in the size of the nuclei of infected cells, and preserve at a later time. Then there is an increase in RNA content in the nucleus, roughly coinciding with the increased content of RNA in the nucleoli.