Theileria parasites were detected in five apparently healthy free-ranging giraffes (Giraffa camelopardalis Linnaeus, 1758) captured for translocation on a game ranch located approximately 60 km south west of Lusaka. Giemsa-stained blood smears examined under a light microscope showed characteristic oval and rod shaped intra-erythrocytic piroplasms. Polymerase chain reaction (PCR) products targeted on the 18S rRNA gene showed characteristic bands of Theileria spp. The average number of infected blood cells per field examined by light microscopy was estimated at 48.6% (n=50, SD±8.2%). The mean white blood cell count (WBC), red blood cell count (RBC), haemaglobin and packed cell volume (PCV)(%) for the five giraffes were estimated at 8.0 x 103/μl, 7.9 x 106/μl, 17.8 g/dL and 41.8%, respectively, being within the normal range of hematological values of free-ranging healthy giraffes. Tick species collected from the infected animals included Rhipicephalus appendiculatus, Rhipicephalus spp., Amblyomma variegatum and other Amblyomma species. To our knowledge, this is the first report of Theileria spp infection in giraffe in Zambia. These findings suggest that wildlife kept on game ranches could serve as carriers of Theileria piroplasms without expressing clinical signs of theileriosis even when infected with a high parasitemia. As such, it is likely that these wildlife reservoirs could play an important role on the epidemiology of theileriosis in Zambia, although detailed follow-up studies are required to determine the intra- and interspecies transmission among wildlife as well as between wildlife and livestock.