The authors evaluated in a group of 217 HIV positive patients the mutual relationship of the number of CD4+T lymphocytes and the level of the viral load of HIV RNA. Using correlation analysis evidence was provided of a not very marked negative correlation of the two indicators. As it was assumed that the relationship of the two parameters is influenced by the applied therapeutic procedures which reduce in particular the viral load, the two parameters were evaluated in relation to treatment. The closest relationship of the two investigated parameters was found in the group treated by monotherapy with zidovudine, followed by the group treated with a combination of two preparations (two nucleoside inhibitors of reverse transcriptase). In the group treated by three preparations (two nucleoside inhibitors of reverse transcriptase and a protease inhibitor) the relationship of the two parameters was least close. Investigation of the level of the viral load of HIV RNA and number of CD4+T lymphocytes is of major importance for the introduction of antiretrovirus treatment and selection of a suitable combination of antiretrovirus preparations. It makes it also possible to follow up the effectiveness of this treatment.