A needleless syringe device for accelerating particles into a target tissue of a vertebrate subject. The syringe comprises an elongate, tubular duct having a lumen for delivering the particles towards the target tissue. Preferably the duct has a constant cross-sectional area. The device further comprises a receptacle holding the particles and a gas discharge chamber upstream of the receptacle. On actuation the gas discharge chamber discharges pressurised gas having a maximum total pressure of less than 10 bar.
