Forty-eight free-ranging red deer (Cervus elaphus) were immobilized with xylazine (X) and tiletamine-zolazepam (TZ) by dart injection during winter 2008 in Norway. A follow-up study in five animals during winter 2010 included arterial blood samples analyzed with a portable clinical analyzer in the field. Thirty-five of 48 animals were effectively immobilized and 13 required a second dart. Mean±SD doses were 2.89±0.45 mg X/kg and 2.89±0.45 mg TZ/kg in calves and 2.97±0.66 mg X/kg and 1.91±0.43 mg TZ/kg in adults. Mean induction times for calves and adults were 8.5±5 min and 11.6±5.5 min, respectively. The main physiologic side effect during immobilization was hypoxemia (pulse oximetry, SpO₂<85%). All five animals evaluated with arterial blood gas samples were hypoxemic (PaO₂<10 kPa). Xylazine was antagonized with 0.43±0.19 mg/kg and 0.27±0.05 mg/kg of atipamezole in calves and adults, respectively. Time to standing/walking in calves and adults was 12±7 min and 12±11 min, respectively. Two capture mortalities occurred.