Summary Fifteen strains of influenza C virus were isolated from abattoir pigs in China in 1981 and antibody against influenza C virus was found in pig sera. Virus survey also showed seasonal activity of influenza C virus in pigs. Additionally, experimental infection of pigs with influenza C virus demonstrated that Chinese domestic pigs could be infected by influenza C virus and that the virus could be transmitted from pig to pig. These results indicate that, like influenza A, influenza C virus can cause natural infection in pigs. To our knowledge, this is the first report of such a finding.