The invention provides an article of manufacture comprising a substantially non-immunogenic injectable collagen for implantation into humans. The invention further provides methods for preparing injectable collagen material by removing collagen-containing material from a non-human animal; washing in saline and alcohol; subjecting material to cellular disruption treatment; and digesting the material with a proteoglycan-depleting factor and/or glycosidase and optionally following with a capping treatment. The invention also provides an article of manufacture produced by the method. The injectable collagen material of the invention are substantially non-immunogenic and have substantially the same mechanical properties as a corresponding native soft tissue.