A watertight cast cover for protecting a cast, bandage or the like includes an elongated, generally tubular waterproof member having a closed end and an open end. An adjustable resilient sealing band extends around the periphery of the open end of the member. The band includes overlapping ends, one end of which defines a flap. The flap and band may be stretched to form a seal with the user's limb and the flap is securable to the band.