Method: Descriptive study. After received the warning of CDC about H3N2 virus on 26 November, 2011, all of 14 Vietnamese cases infected with H3N2 who were identified from January to December 2011 in southern Vietnam were tested by laboratory detection of Swine-Origin Triple Reassortant Influenza A (H3N2) with the A (H1N1) pdm09 virus M gene (SOIVtrH3N2-M) (1). Results: one new strain of A (H3N2) was isolated from the 14 isolations of A (H3N2) in 2011.