The oral appliance for the treatment of sleep apnea provides greater comfort to the user and maintains an open air passage through the mouth by preventing the tongue from blocking the windpipe during sleep. The appliance has a mouthpiece including a frame of hard material and a tooth tray of softer material that conforms closely to the tooth pattern of the user. A spoon-like tongue depressor extends adjustably from the forward center of the device, the tongue depressor having a downward convex bowl that holds the tongue away from the windpipe of the user. The tongue depressor has a stein captured by and rotating in the adjuster, so that the tongue depressor may be prevented from rotating as the adjuster is threaded inwardly or outwardly in the front of the device. An air passage is preferably provided to each side of the tongue depressor adjuster.