An autoinjection device includes a main body 12 in the front end of which is slideably mounted a drawer or front body portion 14. The drawer can be opened to remove or insert a syringe. Closing the drawer while pressing a multifunction button 22 primes the drive mechanism 54, 58 by latching it against trigger latch 66. Pressing the button 22 again while urging the front end causes the drawer to release the trigger latch 66. After the injection the drawer shrouds the used needle and can be released only by pressing the button 22.