Abstract: Fitted bedclothes for rectangular waterbeds comprising a flat substantially rectangular panel member overlying an upper surface of the mattress and an upper portion of the mattress sides. A right-triangular pocket member is connected to at least two panel member corners, forming pockets therebetween and being adapted for receiving a waterbed mattress corner therein. An extensible portion of a free edge of each pocket member resiliently engages a lower corner surface of said mattress, opposingly and diagonally pulling the bedclothes taut over the mattress.