Influenza A virus genome consists of 8 negative-stranded RNA segments. NS1 is a non-structural protein that participates in different steps of the virus infectious cycle, including transcription, replication and morphogenesis, and acts as a virulence factor. hStaufen1, a protein involved in the transport and regulated translation of cellular mRNAs, was previously identified as a NS1-interacting factor. To investigate the possible role of hStaufen1 in the influenza virus infection we characterised the composition of hStaufen1-containing granules isolated from virus-infected cells. Viral NS1 and RNP proteins were identified in these complexes by Western-blot and viral mRNAs and vRNAs were detected by RT-PCR. Also, co localisation of hStaufen1 with NS1, NP and PA in the cytosol of virus-infected cells was shown by immunofluorescence. To analyse the role of hStaufen1 in the infection, we down-regulated its expression by gene-silencing. Human HEK293T cells or A549 cells were silenced using either shRNAs or siRNAs targeting four independent sites in the hStaufen1 mRNA. The yield of influenza virus infections was reduced 5 to 10 times in the various hStaufen1-silenced cells as compared to control silenced cells. The expression levels of viral proteins and their nucleo-cytoplasmic localisation were not affected upon hStaufen1 silencing but virus particle production, as determined by purification of virions from supernatants, was reduced. These results indicate a role for hStaufen1 in late events of the influenza virus infection, possibly during virus morphogenesis.