Open AccessThe successful chemical immobilization of gemsbok Oryx gazella gazella with a new potent analgesic, R33799 (Janssen Pharmaceutica), and the major sedative xylazine hydro-chloride (Rompun; Bayer) is described. Evidence, which is presented, show that the R33799 - xylazine mixture is an improvement over previously used drug mixtures for the immobilization of gemsbok. The following optimal dosage rates and application are recommended: 10-20 ug R33 799 per kg + 100 ug xylazine per kg deep intra-muscularly. It is concluded that with the use of the above-mentioned drug mixtures and deposition site, almost predictable short induction periods of about 5 minutes or less can be achieved. High dosage levels of xylazine was found to produce a delayed or persistent somnolent state which has the disadvantage of a long and hazardous recovery phase, especially in predator prone surroundings. Results show that the action of R33799 could be effectively reversed with the usual morphine antagonists. Propionylpromazine (Combelen; Bayer) was found to be a useful post-capture tranquilizer.