A waterproof cover for casts and/or bandages on limb extremities is formed as a thin-walled elastomeric water-impervious linear tube, preferably made of nitrile, open at at least one end. The cover stretches skin-tight over a limb extremity, and over any and all casts and/or bandages upon the limb extremity, so as to conform to a combined exterior contour of the limb and of any casts and bandages upon the limb. The cover circumferentially squeezes against the limb, sealing watertight both the limb and any casts and/or bandages upon the limb. The waterproof elastomeric tubular cover is comfortable, non-obtrusive, non-obstructive, and easily deployed, removed, and re-deployed.