In the spring of 2013, a novel reassortant avian H7N9 influenza virus containing 6 internal genes from avian influenza H9N2 virus was first identified in the Yangtze Delta region of China. This virus has not been detected in humans or animals prior to that. Thus its emergence led to global public health concerns. In contrast to other previous human H7 infections that mainly manifested as mild illness or conjunctivitis, most H7N9 patients were critically ill and presented severe pneumonia and acute respiratory distress syndrome. Although the first epidemic wave declined quickly after the implementation of active control measurements including the closure of live poultry markets, the second epidemic wave, which began in October 2013 caused almost 300 human infections by the end of April 2014, compared with the first wave`s total of 136. With the rapidly increasing human cases, and the expansion of affected regions, more efforts should be made to prepare for the potential pandemic.