The invention relates to needle-free apparatus that can be used to augment soft tissue. More specifically, the needle-free injectors of the present invention allow injection of more viscous materials such as collagen, hyaluronic acid, and other polymers that are useful as dermal fillers. The needle-free injectors of the present invention allow injection of such materials to fill the undesired lines, wrinkles, and folds of a patient. The present invention also relates to kits comprising such needle-free injectors and a quantity of dermal filling material. In addition, the present invention relates to methods of augmenting soft tissue using needle-free apparatus.