A device for negative pressure wound therapy having a cover material for air-tight sealing of the wound space connected to a negative pressure source; and a wound dressing having an open-cell polyurethane foam. The open-cell polyurethane foam has special properties, in particular a tensile strength after three days of storage in bovine serum, measured in accordance with DIN 53571, between 80 kPa and 300 kPa. The open-cell polyurethane foam may be used as a wound dressing in negative pressure wound therapy.