The present invention provides a needle-free injection device for delivering amedicament under pressure into an animal or human. The injection device includes anactuating device comprising: a gas tight chamber a piston and rod assembly slidablyreceived in the chamber and movable between a forward position and a rearwardposition a gas charge in the chamber for urging the piston and rod assembly tothe forward position means for moving said piston and rod assembly against saidgas charge into the rearward position and a trigger for releasably retaining thepiston and assembly in the rearward position. Also provided is a method and kitfor using the device to administer a liquid through the skin of an animal or human.
