A locking bag includes an envelope with a single opening defined between a pair of side wall edges. A pair of plastic zipper portions are disposed on opposite sides of the single pair of side wall edges. A zipper closure clip is slidably attached to the single pair of side wall edges at one corner of the opening of the bag. The zipper closure clip is adapted to clamp the two portions of the plastic zipper together when the zipper closure clip is slid along the opening of the bag. The two plastic zipper portions include suitable means to make the closing of the opening permanent. In one embodiment, the zipper closure is removable from the bag after the bag is permanently closed.