In January 2015, there was an outbreak of avian-origin influenza A (H7N9) virus in Zhejiang Province, China. A 45-year-old man was admitted to the First Affiliated Hospital of Zhejiang University with a high fever that had lasted 7 days, chills, and a cough with yellow sputum. Laboratory testing confirmed infection with the H7N9 virus, likely obtained from contact with poultry at a local live poultry market. A large dense shadow was apparent in the patient's left lung at the time of admission. Treatment with oseltamivir (75 mg twice daily) did not improve the patient's condition. The decision was made to try using convalescent plasma to treat the infection. Convalescent plasma was administered 3 days after the patient was admitted to the hospital and led to a marked improvement. To our knowledge, this is the first report of the successful use of convalescent plasma to treat a case of H7N9 infection in China. These results suggest that the combination of convalescent plasma and antiviral drugs may be effective for the treatment of avian-origin H7N9 infection.