An injection method for injecting a substance into eggs, and an injection head for implementing said method. The method generally includes piercing the shell and at least the shell membrane of an egg by moving a needle, and then injecting the treatment substance via said needle, said piercing step comprising a first movement of the needle to pierce the shell with a first penetration force and then a second movement of the needle to pierce at least the shell membrane with a second penetration force lower than the first penetration force.
