Detection of influenza virus in respiratory specimens from ill individuals is the most commonly used method to identify influenza virus infection. A number of respiratory specimen types may be used, including swabs, brush, aspirate and wash, and specimens may be collected from numerous sites, including anterior and posterior nasopharynx, oropharynx and nares. Traditionally, respiratory specimens from the nasopharynx were considered to have highest sensitivity for viral detection. However, as molecular assays such as reverse transcription polymerase chain reaction (RT-PCR) have increased the sensitivity of viral detection from respiratory specimens, the use of less invasive and easier to obtain specimens has increased for the detection of influenza. This review presents and evaluates the sensitivities of respiratory specimen methods used in epidemiologic studies that used RT-PCR to detect influenza virus in respiratory specimens from ill patients. This literature review suggested that a combination of two less invasive swabbing methods, such as nasal and oropharyngeal swabs, had about the same sensitivity as nasopharyngeal specimens for influenza detection by RT-PCR. By combining two less invasive collection methods, it may be possible to reduce barriers to enrollment without compromising influenza detection sensitivity.