Abstract: We report here on the expression of the hemagglutinin- neuraminidase protein of the Sendai virus using a T7 RNA polymerase system in BHK-21 cell line. The expression was confirmed by the immunoprecipitation and Western/lmmunoblott techniques. This HN gene expression has confirmed that the T7 RNA polymerase and recombinant vaccinia virus systems can be used for the expression studies. In future we will try to express the HN gene along with other Sendai viral genes in the polarized cells and will try to locate the transport signals in their polypeptide backbones.