One hundred and thirty three "wild" muskoxen, 81 of which of known body mass, were successfully immobilized using etorphine (M99), and xylazine (Rompun®), delivered by use of a dart gun. A dose of 0.05 mg/kg M99, supplemented by 0.15 mg/kg Rompun was found to be very effective. This dose is much higher than currently recommended e.g. by Handbook of Wildlife Chemical Immobilization.