The aim of this study was to determine the epidemiology of influenza infection among patients with influenza-like illness by real-time RT-PCR in southern Thailand from August 2009 to January 2011. The predominant strain in Thung Song District was influenza A. Sporadic cases of influenza occured year round but the incidence peaked from August to November 2009 and July to November 2010. During August to November 2009, pandemic H1N1 (pH1N1) activity was observed along with a low level of seasonal influenza co-circulation. Subsequently, seasonal influenza (H3) activity increased and became the predominant influenza strain, with co-circulation with pH1N1 and influenza B during the 2010 influenza season. Continual surveillance of influenza activity is useful for public health planning in southern Thailand and plays a major role in future influenza control and prevention measures.