Abstract: The present invention relates to an automatic injection apparatus for animals, in particular for chicks, which comprises a housing, a syringe with an injection needle giving the injection through an aperture on the front wall of said housing, a two-way air double action piston being connected to said syringe and to a source of air, activating means for said piston and means for connecting the syringe to a liquid container. Said apparatus has optionally additional parts, e.g. a timer fixing the length of the period of the injection; an air regulator; means for cleaning the air; counters measuring the numbers of animals being injected and/or pre-setting the number of animals to be injected; and a disinfecting device for the needle.