Collared anteaters (Tamandua tetradactyla) were immobilized for clinical procedures as part of a wildlife rescue during the filling of a hydroelectric dam (Petit Saut, French Guiana) from March 1994 to March 1995. Two doses of ketamine hydrochloride (KH) (group I mean +/- SD = 11.2 +/- 1.4 mg/kg, group II = 19.7 +/- 1.3 mg/kg) in combination with xylazine hydrochloride (XH) (1.0 +/- 0.1 mg/kg) were evaluated in seven and 10 collared anteaters, respectively. Induction time did not differ between the two groups. Immobilization time was significantly longer in group II than in group I (48.3 +/- 15.8 min and 35.0 +/- 9.5 min, respectively), without lengthening the recovery process. Adverse effects were not observed. The degree of anesthesia and the muscle relaxation were better in group II than in group I. Rectal temperature decreased in both groups and was significantly higher in group II than in group I. Heart rate was significantly higher in group II than in group I at 5 min post-injection and decreased in group II. No effects on respiratory rate were observed. We recommend the 20 mg/kg KH -1 mg/kg XH combination, especially for manipulations longer than 30 to 40 min and for minor surgery procedures.