In the last 4 years, incidences of endemic or epidemic respiratory diseases associated with canine influenza H3N2 virus in Asian dogs have been reported in countries such as South Korea and China. Canine species were considered to be the new natural hosts for this virus. However, at the beginning of 2010, influenza-like respiratory signs, such as dyspnea, were also observed among cats as well as in dogs in an animal shelter located at Seoul, South Korea. The affected cats showed 100% morbidity and 40% mortality. We were able to isolate a virus from the lung specimen of a dead cat that had suffered from the respiratory disease, in embryonated chicken eggs. The 8 viral genes isolated were almost identical to those of the canine influenza H3N2 virus suggesting interspecies transmission of canine influenza H3N2 virus to the cat. Moreover, 3 domestic cats infected with intranasal canine/Korea/GCVP01/07 (H3N2) all showed elevated rectal temperatures, nasal virus shedding, and severe pulmonary lesions, such as suppurative bronchopneumonia. Our study for the first time shows that cats are susceptible to canine influenza H3N2 infection, suggesting that cats may play an intermediate host role in transmitting the H3N2 virus among feline and canine species, which could lead to the endemic establishment of the virus in companion animals. Such a scenario raises a public health concern, as the possibility of the emergence of new recombinant feline or canine influenza viruses in companion animals with the potential to act as zoonotic infection cannot be excluded.