Multiplex reverse transcription polymerase chain reaction (multiplex RT -PCR) method was developed for the simultaneous detection and typing of parainfluenza viruses (PIVs) which are an important cause of respiratory morbidity. The primer pairs for the multiplex RT-PCR were designed based on the nucleotide sequences of hemagglutinin-neuraminidase (HN) coding region of the genomic RNA. Multiplex RT-PCR yielded specific products for each type of PIVs and did not show the cross reaction with other respiratory viruses, such as adenoviruses, respiratory syncytial viruses (RSV), and influenza viruses. In comparison with the immunofluorescence assay (IFA), the multiplex RT-PCR method was 100 times more sensitive than IFA. These results suggest that the multiplex RT-PCR may be useful for the specific and rapid detection and typing of PIVs 1, 2 and 3 in a single-tube reaction.