MANY PEOPLE HEAT THEIR HOMES WITH WOOD-BURNING STOVES. However, toxic fire effluent can escape from old or improperly operated stoves. The authors describe a case in which bronchiolitis obliterans developed in a man within hours after he burned synthetic construction materials in his wood-burning stove. Certain factors, such as careless or improper use of the stove, the size of the room, the lack of open-air ventilation and the composition of the materials burned, strongly point to inhalation of the fire effluent as the cause.