Non-denatured triple-helix collagen extracted from animal tendons and skin is purified and brought into the form of a stable, sterile, sterile and meterable powder having a particle size of not more than 20 microns. The powdered collagen so obtained has favourable characteristics of distribution and asepsis and is particularly efficacious in the more delicate phases of the wound-healing process compared with powdered collagens obtained by known methods.