Background. No information is available on the viral etiology of upper respiratory tract infections in Cameroon. Methods. We prospectively enrolled outpatients with influenza-like illness (ILI) presenting at 14 sentinel clinics located across the country from January through December 2009. The specimens were tested using real-time and multiplex reverse-transcription polymerase chain reaction methods for the detection of 15 RNA respiratory viruses. Results. We detected at least 1 respiratory virus in 365 of 561 specimens (65.1%). Overall, influenza virus was the most commonly detected virus (28.2% of specimens), followed by human rhinovirus (17.8%); parainfluenza virus (PIV) types 1-4 (7.5%); enterovirus (5.9%); respiratory syncytial virus (RSV; 5.7%); human coronavirus (HCoV) OC43, 229E, NL63, and HKU1 (5.3%); and human metapneumovirus (HMPV; 5.0%). RSV (26 of 31 specimens 83.9%), PIV (30 of 39 76.9%), and HRV (64 of 99 64.6%) were most common among children < 5 years of age. Coinfections were found in 53 of 365 positive specimens (14.5%), and most (71.7%) were in children < 5 years of age. While influenza virus, enterovirus, RSV, and HMPV had a defined period of circulation, the other viruses were detected throughout the year. Conclusions. We found that respiratory viruses play an important role in the etiology of ILI in Cameroon, particularly in children < 5 years of age.