Dendritic cells (DC) are believed to play an important role in the initiation of innate and adaptive immune responses to infection - including respiratory tract infections where respiratory dendritic cells (RDC) perform this role. In this report, we examined the susceptibility of isolated murine RDC to influenza virus infection in vitro and the effect of multiplicity of infection (MOI) on costimulatory ligand upregulation and inflammatory cytokine/chemokine production after infection. We found that the efficiency of Influenza infection of RDC increased with increasing MOI. Furthermore, distinct subpopulations of RDC differed in their susceptibility to influenza infection and in the magnitude/tempo of costimulatory ligand expression. Additional characterization of the CD11c(+) RDC revealed that the identifiable subsets of RDC differed in susceptibility to infection with CD11c(+)CD103(+) DC exhibiting the greatest susceptibility, CD11c(+)CD11b(hi) exhibiting intermediate susceptibility and CD11c(+) B220(+) plasmacytoid DC (pDC) exhibiting the least susceptibility to infection. A companion analysis of the in vivo susceptibility of these RDC subsets to Influenza revealed a corresponding infection pattern. These three RDC subsets displayed different patterns of cytokine/chemokine production in response to influenza virus infection in vitro: pDC were the predominant producers of most cytokines examined, while CD103(+) DC and CD11b(hi) DC produced elevated levels of KC, IL-12p40 and RANTES in response to influenza infection. Our results indicate that RDC are targets of influenza infection and that distinct RDC subsets differ in their susceptibility and response to infection.