Abstract: A holder for maintaining flexible plastic bags, of the type having a pair of handle loops, in an open upright position useful as a trash receptacle includes a pair of thin, uniform cross-section end panels and at least one pair of thin, uniform cross-section side rails. Snap fasteners at each end of each side rail are provided to insertably receive the edge of an end panel, permitting a rectangular, open box-like structure to be constructed by the user, without tools, from a generally flat package of component parts. A cutout in the upper portion of each end panel has one or more downwardly projecting tabs formed in the upper edge wall of the cutout. Each handle loop of a flexible plastic bag placed in the open center of the holder may be looped over the upper edge wall of an adjacent end panel, and looped around a selected finger tab or tabs to retain the bag in an open, upright position within the holder.