SummaryWe compared the technique of immunofluorescence on clinical samples (IFCS) and immunofluorescence on centrifuged cell cultures (IFCC) for the detection of respiratory viruses, using monoclonal antibodies.Four hundred fourty five nasopharyngeal aspirates were tested prospectively for RSV, influenza-(A and B), parainfluenza viruses (1, 2, 3) and adenovirus. IFCS and IFCC detected 94% and 51% of RSV respectively, 78.5% and 82% of influenza viruses, 8.3% and 100% of parainfluenzaviruses and 0 and 100% of adenoviruses.We conclude that for routine rapid virus diagnosis the IFCS procedure is acceptable for RSV, that for influenza virus the IFCC procedure can be omitted for samples positive by IFCS, and that for the detection of parainfluenza and adenoviruses the IFCS procedure is too insensitive.