Background. HIV/AIDS pandemy has hit the entire world. With the use of retroviral therapy the disease became chronic. The life prolongation often leads to complications in various organs. The aim of our work was to determine the frequency of blood count pathology at the time when the HIV infection was diagnosed, that means before any antiretroviral treatment was administered, and its relation to the disease stage. Method and Results. Out of 70 patients registered in AIDS centre in Brno University Hospital by 1st March 2006, we have complete blood count results including absolute number of CD4+ lymphocytes. Out of these 70 we evaluated a group of 64 HIV-positive individuals (17 women, 47 men), who were examined at the time the disease was diagnosed. Average and medians of all blood count parameters were within the reference range, only CD4+ lymphocytes in 1 mm3 were out of range. Pathology in red blood cells count was found 26 times (41.9 % of examined patients), in white cell count 22 times (35.5 %). Thrombocyte number was affected 3 times, and only in one of these cases it was a separate finding. Conclusions. Blood count pathology is relative frequent in the HIV infected. Therefore HIV infection should be considered as one of the possible causes of unexplained blood count pathology.

        Key words: HIV infection, blood count pathology, HIV infection stages.