Reticuloendotheliosis virus (REV) causes an immunosuppressive, oncogenic, and runting syndrome in many avian hosts worldwide. The immunosuppression caused by REV can decrease the antibody levels of vaccines and subsequent increase susceptibility to secondary infections. There are no commercial vaccines or effective drugs to control REV infections at present. To investigate the REV infection status in chickens in China, 25,224 sera from 573 chicken flocks, collected between 2005 and 2015, were measured for REV antibodies using an enzyme-linked immunosorbent assay. The seroprevalence of REV antibodies in the flocks was 56.20% (322/573) and the overall seroprevalence in individual chickens was 13.91% (3,509/25,224). Of the 23 regions sampled, all provinces, except Heilongjiang, produced positive samples. Guangxi had the highest rate, of 57.84%. The virus-positive rate also tended to increase as the chickens aged. Our study indicates that REV infection has been common in China over the past decade.