More than 80% of the cases of respiratory infections in children are of viral origin. Viral culture has been the reference method for the diagnosis of viral respiratory infections for years, but there is now a tendency to replace viral culture by molecular biology techniques, notably real-time PCR-based assay, because of its excellent sensitivity and good feasibility. Currently in most laboratories, however, diagnosis of viral respiratory infections is still done using techniques based on detection of viral antigens, especially immunofluorescence assays. Rapid diagnostic tests for use outside of laboratories are now available on the open market, and even if their sensitivity remains lower than that of other techniques, it is likely that they will become widely used, especially in doctors' offices, in the near future. New methods for the diagnosis of viral infections based on DNA microarray technologies are currently under investigation and appear to be very promising.