Current jet injection devices often utilize compressed air or springs to create a high-pressure fluid jet capable of piercing the skin. However, these devices are limited to a single invariable injection profile based on the impulse created by the compressed air or spring and therefore the parameters that affect injection are not well understood. To determine the effect of injection parameters on jet injection into tissue, including the effect of the fluid ejection profile on the injection, a controllable jet injection device was used to perform experiments into sheep and pig tissue. This paper demonstrates the importance of an initial peak in injection pressure and a subsequent lower follow-through pressure for successful jet injection into sheep and pig tissue.