Two cases of Theileria sp. infection in wild Chinese water deer (Hydropotes inermis argyropus) were diagnosed by microscopic examination of thin blood smears and by molecular typing. Two wild Chinese water deer were referred to the Veterinary Medical Center of Chungbuk National University in South Korea, presumably the result of traffic accidents. Thin blood smears, which were stained with Giemsa, revealed intraerythrocytic parasites; however, the deer had no remarkable findings on physical examination. Polymerase chain reaction and direct sequencing indicated that the parasite was nearly identical to the unidentified Theileria sp. previously found in China. Phylogenetic analysis showed that the Theileria sp. identified in these cases are closest to the group of unidentified Theileria spp. previously found in China and Japan.