An injection device comprises a housing (40) for containing a syringe or cartridge (14) of medicament a rotary drive shaft (20) for being rotated by an adjustable preset amount to cause expression of a corresponding amount of medicament from said syringe or cartridge a torsion drive spring (24) anchored at one end region relative to said drive shaft (20) and at its other end region being secured to a fitting (44) adapted to non rotatably engage a seat (48 50) on said housing.
