Impala (Aepyceros melampus) and eland (Taurotragus oryx) were immobilized with a xylazine-etorphine-acepromazine combination or with xylazine alone. Clinical observations were made and blood samples were taken at intervals to determine the drug effects on clinical and blood parameters. During the immobilization period heart rate and body temperature decreased, as well as numbers of circulating erythrocytes and leukocytes, and values for haemoglobin and packed cell volumes. The possible causes are discussed.