The rates of transmission of oxygen and carbon dioxide through various burn wound dressing materials were determined. The British Standard Vacuum technique was used to determine the Gas Transmission Rate (GTR) of hydrophobic dressings. A Gas to Liquid technique was used to determine the GTR of hydrophilic (water containing) dressings. All the materials tested showed greater GTR values for carbon dioxide than for oxygen. The role of the transmission characteristics of the dressings to influence the wound healing environment is discussed.