Influenza can cause severe complications in HIV infected individuals leading to increases in hospitalisation and mortality. Vaccination is recommended for such individuals, but some studies reported that immunisation against influenza may stimulate an increase of HIV viral load and decrease of CD4+ cells count. A review of published studies, including our study carried out in HIV former drug addicts, indicates that vaccination against influenza is well tolerated in both children and adult individuals with HIV, but response to vaccination is lower than that observed in immunocompetent individuals. Most studies, including our own, show that vaccination does not induce significant changes in viral load and CD4+ cell counts. In studies reporting modifications of such parameters there is a general agreement that the increased viral replication is usually transient and unable to determine a clear, measurable progression of the underlying HIV disease. Therefore, vaccination against influenza can be safely administered to HIV infected people.