Field immobilization of captive antelope may be required for medical examination, blood sample collection, and animal identification. The aim of this study was to evaluate the effects of a combination of butorphanol, detomidine, and midazolam (BDM) and its partial reversibility in Nile lechwe antelope (Kobus megaceros). Nine captive lechwes, weighing 28–64 kg, were immobilized, in February 2011, with butorphanol 0.20±0.05 (mean±SD) mg/kg, detomidine 0.20±0.05 mg/kg, and midazolam 0.31±0.08 mg/kg administered intramuscularly (IM) with a blowpipe. Physiologic parameters and depth of anesthesia were recorded when the animals became recumbent at 19.55±8.36 min after darting (T0) and after 10 (T10), 20 (T20), and 30 (T30) min. An arterial blood sample was collected at T20. At the end of the procedures, immobilization was partially reversed with atipamezole 0.25 mg/kg IM. Quality of induction, immobilization, and recovery was scored. The BDM combination induced immobilization and lateral recumbency in 13.44±5.61 min. Median induction score (scored 1 [excellent] to 4 [poor]) was 1 (range 1–2). Heart rate varied 40–104 beats/min, respiratory rate 16–108 breaths/min, and rectal temperature 36.5–40.3 C. Hyperthermia was observed and rapidly treated in three animals that demonstrated insufficient immobilization after darting. Arterial blood gas analyses revealed a mean pH of 7.43±0.07, partial arterial pressure of CO₂ of 44.1±6.0 mmHg, partial arterial pressureof O₂ of 74.0±13.5 mmHg, and an arterial O₂ saturation of 94.77±3.96%. Recovery was smooth and animals were walking in 13.44±7.85 min. Median recovery score (1 = excellent to 4 = poor) was 1 (range 1–2). The BDM was effective in immobilizing captive healthy lechwes with minimal cardiorespiratory changes.