In mid-February 2006, an outbreak of Highly Pathogenic Avian Influenza (HPAI) H5Nl affected the commercial poultry production sector and backyards in Egypt and resulted dramatic economic losses to the poultry industry of Egypt and continue to pose a serious threat to public health. The present study was designed for detection and isolation of Avian Influenza Viruses (AIV) circulating among poultry since their first detection in 2006. Tracheal and cloacal swabs were taken from the freshly dead birds. Till now (2010) the tested swab samples were inoculated into the allantoic cavity of 911-day-old SPF embryonated chicken eggs (ECE) for virus isolation. The allantoic fluids (AF) of the inoculated ECE were examined for detection of avian influenza (Al) isolates using rapid haemagglutination test (HA). It was found that, all the inoculated isolates caused high mortalities up to 100% for the embryos 24-48hrs post inoculation and gave very strong RBCs agglutination. The haemagglutination positive samples were identified and subtyped antigenically by serological tests using Haemagglutination inhibition test (HI) using standard Al antisera and genetically by RT-PCR using specific primer. All the isolates were confirmed to be H5N1 and grouped according to the year of isolation as 2006, 2007, 2008, 2009 and 2010 group isolates. The HA titers of the above mentioned isolates were 6, 7, 8, 7 & 7 respectively. All the isolated Al viruses were titrated in ECE and examined for determination of their pathogenicity in specific pathogen free (SPF) 4-6 week old chicken. All the Al isolates proved to be HPAI viruses where the Intravenous Pathogenicity Index (IVPI) score for them were 2.1, 2.5, 2.3, 2.2 & 2.3 and their titers in ECE were 10.1, 9, 9.3, 9.3 and 10 Logo10 EID50/ ml for 2006, 2007, 2008, 2009 and 2010 isolates respectively.