Highly pathogenic avian influenza (HPA1) virus of H5N1 subtype has spread worldwide and continues to cause outbreaks in poultry and sporadic human infections since 2003. As of 9 April 2010, 493 confirmed human cases including 292 fatal cases were reported from 15 countries. Despite emergence of the pandemic A (H1N1)2009 virus, pandemic threats posed by H5N1 subtype virus still remain. H7 subtype avian influenza viruses also pose a similar threat to humans as H5N1 subtype virus. We provide here an updated overview on the human infections of HPA1 viruses in the world.