Infections with the human immunodeficiency virus 1 (HIV- 1) lead to the acquired immunodeficiency syndrome (AIDS), resulting in the establishment of a wide range of severe opportunistic infections. Since the introduction of the highly active antiretroviral therapy (HAART) into the treatment of HIV infections, in many cases a delayed appearance of AIDS-defining diseases is achievable. Life expectancy of antiretrovirally treated HIV-infected people applying HAART could be considerably extended and now resembles that of several other chronic diseases. For the initial treatment of HIV-1 infection, an adjunction with three antiretroviral agents is generally used. In most cases, the application of two nucleoside or nucleotide reverse transcriptase inhibitors (NRTI) together with a non-nucleoside reverse transcriptase inhibitor (NNRTI), a protease inhibitor (PI) or an integrase inhibitor (II) is recommended. Before and during antiretroviral treatment, antiretroviral drug resistances, individual tolerance profiles and the needs of the individual patient, as well as several interactions with other drugs have to be considered. Diagnostics of HIV infection is based upon the proof of specific antibodies.