The outbreak of human infections caused by the novel avian-origin H7N9 subtype influenza viruses in China since March 2013 underscores the need to better understand the pathogenicityand transmissibility of these viruses in mammals.In a ferret model, the H7N9 influenza virus was found to be less pathogenic than a H5N1 virus but was comparable withthe 2009 pandemic H1N1 virus, based on the clinical signs, mortality, virus dissemination, and histopathological analyses. The H7N9 virus could replicate in the upper and lower respiratory tract, heart, liver, and olfactory bulb. It is worth noting that the H7N9 virus exhibited low level of transmission between ferrets via respiratory droplets. There were four mutations in the virus isolated from the contact ferret which were D678Y in PB2, R157 K in HA(H3 numbering), I109T in NP, and T10I in NA. These data emphasized that the avian-origin H7N9 subtype influenza virus has the ability to transmit between mammals, highlighting the potential of human-to-human transmissibility