Influenza can be manifested as an acute febrile illness, with symptoms similar to many pathogens endemic to Cambodia. The objective of this study was to evaluate the Quickvue influenza A+B rapid test to identify the etiology of acute febrile illness in Cambodia. During December 2006-May 2008, patients enrolled in a study to identify the etiology of acute febrile illnesses were tested for influenza by real-time reverse transcriptase PCR (RT-PCR) and Quickvue influenza A+B rapid test. The prevalence of influenza was 19.7% by RT-PCR. Compared with RT-PCR, the sensitivity and specificity of the rapid test were 52.1% and 92.5%, respectively. The influenza rapid test identified the etiology in 10.2% of enrollees and ≥ 35% during peak times of influenza activity. This study suggests that rapid influenza tests may be useful during peak times of influenza activity in an area where several different etiologies can present as an acute febrile illness.