Theileria spp. are intracellular protozoa transmitted by ixodid ticks. T. parva and T. annulata are highly pathogenic and responsible for serious disease in domestic ruminants in tropical and subtropical countries. However, asymptomatic findings of Theileria sp. in wild ungulates lead to the suggestion that wild ruminants play a role as reservoirs for these piroplasms. In a game enclosure in Eastern Austria (Federal county of Burgenland), piroplasms were detected with molecular analysis in blood samples of all 80 examined asymptomatic red deer (Cervus elaphus). Furthermore, piroplasms were detected in four out of 12 questing nymphs of Haemaphysalis concinna. In 32 Ixodes ticks sampled on-site, no Theileria DNA was detected. Sequence analysis identified these samples from both red deer and ticks as Theileria sp. ZS TO4. Our findings indicate that farmed red deer serve as asymptomatic carriers and adapted intermediate hosts of Theileria sp. in Central Europe and H. concinna was identified as a possible vector species of Theileria sp. ZS TO4.