Clinical suspicion of a primary HIV infection is aroused by the patient's exposure history and can only be confirmed by an HIV PCR test. The classic HIV antibody test (ELISA) often is non-reactive during the very early stage of HIV infection. The value of antiviral therapy during primary HIV infection is unclear. In spite of a positive influence on surrogate markers in vitro, studies so far have not been able to demonstrate a clinical benefit. Treatment should be carried out only in specialized infectious disease centers, most preferably within controlled clinical studies.