During November and December of 1988, 1990, and 1991, a total of 22 free-ranging Juan Fernández fur seal (Arctocephalus philippii) females from Alejandro Selkirk Island, Juan Fernández Archipelago, Chile, were immobilized with a combination of ketamine and diazepam. Atropine sulphate was used to decrease respiratory secretions. The mean (±SD) induction dosages of ketamine and diazepam were 3.64 ± 1.3 mg/kg and 0.12 ± 0.07 mg/kg, respectively. Mean (± SD) induction time and time to recovery for females injected intramuscularly (IM) (15 ± 7 min and 47 ± 16 min) were significantly greater than for females injected intravenously (IV) (0.6 ± 0.4 min and 26 ± 11 min). Mean (± SD) heart rates and core temperatures were significantly higher for females injected IV (173 ± 15.71 beats/min and 37.6 ± 0.83 C) than for females injected IM (135 ± 27.06 beats/min and 36.5 ±1.15 C). In addition, the IV route resulted in better levels of immobilization compared to the IM route. The degree of immobilization was not related to the dosages of ketamine and diazepam administered. Two animals died after drug administration.