A convection blanket for warming persons lying thereon. The preferred embodiment has four layers, two outer insulating layers, and two inner layers of metallic foil. The inner metallic layers minimize heat loss across the length of the blanket. A unique pattern of pinholes in the top layers allows a larger volume of warm air to exit the blanket at the end opposite the air supply hose. All layers are stitched intermittently to avoid distension of the blanket, without defining clear channels, assuring uniform distribution of air within the blanket.