Twenty-three gemsbok in the Namib Desert were captured with combinations of. fentanyl or etorphine hydrochloride, hyoscine hydrobromide and tranquilizers such as azaperone, SU 9064, triflupromazine hydrochloride and acetylpromazine maleate. Fentanyl, a New imbolizing compound, proved to be a safe and effective immobilizing drug for capturing gemsbok.