Accurate telemetric heart-rate and body-temperature measurement in wildlife requires surgical implantation or transmitters. We describe a field surgical protocol used to subcutaneously implant 25 transmitters in the ventrolateral base of the neck of 13 adult red deer (Cervus elaphus) and document medical effects of the procedure. The method was an improvement over other implantation techniques. The initial aseptic surgical procedure lasted 46 minutes (37-66 min), and no medical complication occurred in 92% of the experiments. In contrast, implant replacement led to complications in 42% of the cases. However, all deer with medical complications recovered completely and were in good general condition when recaptured. No deer died from surgery or from implant complications. Eight deer carried an implant for >1 year without complications, the longest period being 1,145 days. This technique can be applied to captive and free-ranging deer. However, it requires careful preparation, availability of reliable biotelemetry devices, and sterile surgical procedures. Transmitter replacement should be avoided to minimize complications associated with implants.