Importantly, we found that both H5N6 viruses isolated from wild birds were highly pathogenic and could efficiently be transmitted in chickens. Both viruses were shed from the oropharynx and cloaca in inoculated chickens and could be efficiently transmitted from infected chickens to naïve contact groups, the latter of which also shed viruses from both the cloaca and oropharynx throughout the experimental period. That the H5N6 HPAIVs isolated from wild birds could infect and be transmitted in chickens suggests that they may co-circulate in poultry and thus pose a great threat to the poultry industry.