Both ehrlichioses and anaplasmoses are zoonotic, fatal infectious diseases that caused by ticks. White-tailed deer (Odocoileus virginianus) are important hosts for Ehrlichia chaffeensis, Anaplasma phagocytophilum and Anaplasma-like organisms. In the present study, an evaluation of infection with tick-borne pathogens was conducted using a PCR assay on the blood of a deer that expressed anorexia and decreased activity. The results of the PCR assay revealed natural co-infection of E. chaffeensis and A. bovis in the deer. This indicates that deer may be a natural reservoir of both E. chaffeensis and A. bovis in South Korea.