Abstract: A ventilation system is disclosed for a cast of the type which encompasses a limb with a rigid material such that an inside surface of the cast faces the limb while an outside surface of the cast is spaced outwardly from the inside surface. The ventilation system includes a tube insertable through the cast so that one end of the tube is open to the limb while the other end of the tube is open to the outside surface of the cast. A source of pressurized air is then fluidly connected to the other or outside end of the tube thus forcing air flow through the tube and into the area between the inside surface of the cast and the limb.