ABSTRACT:Four medetomidine/ketamine (M/ K) doses (30 mg/kg/3 mg/kg; 40/4; 50/5; 60/6), administered by intramuscular injection, were evaluated for short-term immobilization of adult male variable flying foxes (Pteropus hypomelanus). The highest dose (60 mg/kg/ 6 mg/kg) produced a significantly faster induction (31646 sec) than the lowest dose (30/ 3) (125662 sec). The highest dose levels (50/5, 60/6) produced significantly longer immobilization times (52.5625.7 min and 60.66 20.8 min, respectively) than did the lower doses (30/3, 40/4) (18.868.7 min and 31.0614.3 min, respectively). The dose at which 50% of the bats were immobilized for $30 min (ED 50 ) was approximately 40 mg/kg/4 mg/kg. This dose produced a mean immobilization time of 31614 min, bradypnea and bradycardia. In conclusion, a M/K dose of 50 ug/kg/5 mg/kg is recommended for greater than 30 min of relaxed immobilization in free-living variable flying foxes and is sufficient for safe collection of samples.