"An apparatus for facilitating the healing of a wound, comprising vacuum means for creating a negative pressure on the area of the skin including and surrounding the wound and sealing means operatively associated with said vacuum means for maintaining said negative pressure on said wound by contacting the skin surrounding said wound, characterised in that said negative pressure is between about 0.01 and 0.99 atmospheres, and in that said apparatus comprises screen means for positioning at the wound within the sealing means for preventing overgrowth of tissue at the wound in which said screen means comprises an open-cell polymer foam."