Abstract: This invention relates to an improved waterproof case for padlocks and, more specifically, to a means for sealing the apertures in such a case at the points where the legs of the shackle enter the latter, such means comprising a self-centering flexible tube loosely fitting the shackle and with the ends thereof engaging either the lid of the case directly or an O-ring seal interposed therebetween to maintain a continuous annular fluid-tight seal around the aforementioned shackle-receiving openings when the shackle is closed and locked. In those versions where the tube ends engage the lock case lid directly to effect the seal, an upstanding annular rib terminating in a feathered edge that functions to enter and flare the tube end and, in so doing, form a fluid-tight annular seal therewith.