HIV infection is diagnosed using serological tests (detection of HIV1/2-specific antibodies) and tests based on molecular biology techniques (detection of viral nucleic acids: HIV RNA, HIV DNA). Currently, infection with HIV mediated by blood-derived preparations is practically impossible. HIV-specific antibodies pass through placenta to foetal blood, where they may persist till 18^th month of life and, therefore, serological tests in children below this age may be falsely positive, which makes establishing a correct diagnosis more difficult. In Poland, only 10% of pregnant women undergo tests aimed to detect infection with HIV while in some Western countries such tests are performed in as many as 98% of pregnant women. During pregnancy in a HIV(+) woman, HIV blood load and number of

Th CD4+ lymphocytes should be monitored. In Poland, compulsory tests for presence of HIV infection are performed in persons suspected of HIV infection/AIDS; newborns and infants, pregnant women, carriers and individuals in contact with the infected material.