Twenty great apes (six orangutans, eight chimpanzees and six gorillas) were anaesthetised prior to being transported for undergoing diagnostic and interventional procedures. Anaesthesia was induced with a combination of medetomidine and ketamine administered intramuscularly through a dart syringe. The onset of anaesthesia varied among apes: the mean (±sd) time from darting to recumbency was 12.13 (±1.9), 18.5 (±8.7) and 22.2 (±9.2) minutes in chimpanzees, orangutans and gorillas, respectively. The depth of anaesthesia was sufficient to allow safe removal of the animals from the enclosure, intravenous catheter placement and manipulation; however, the anaesthetic effect was short-acting (20 (±7) minutes in orangutans, 16 (±14) in gorillas, and 10 (±4) minutes in chimpanzees, respectively) and isoflurane administration was necessary in the majority of the apes to prolong the duration of anaesthesia, especially when lengthier procedures were performed. The sedative effect of medetomidine was reversed at the end of each procedure with atipamezole, and recovery was smooth and uneventful for all animals.