An injection device (210 110) is described. A housing (212 112) receives a syringe and includes a return spring (226 126) for biasing the syringe from an extended position in which its needle (218 118) extends from the housing (212 112) to a retracted position in which the it does not. A drive spring (230 130) acts on a first drive element (232 132) and a second drive element (234 134) acts upon the syringe to advance it from its retracted position to its extended position and discharge its contents through the needle. The first drive element (232 132) is capable of movement relative to the second (234 134) once a nominal decoupling position has been reached. A release mechanism is activated when the first drive element (234 134) is further advanced to a nominal release position, to release the syringe (214 114) from the action of the drive spring (230 130), whereupon the return spring (226 126) restores the syringe (214 114) to its retracted position. The nominal decoupling and release positions are defined relative to the syringe (214 114). This may be achieved by interaction between a moving component and a decoupling component (162 262) that moves with the syringe as it is advanced.
