Abstract: A modular utility cart includes four corner posts, at least one intermediate shelf and a top shelf. The cart incorporates improved structures for securing the intermediate and top shelves to the posts. Specifically, each intermediate shelf is formed with four open collars each for embracing one post. Each collar has a cross-section substantially congruent to the cross-section of the associated post, and has an upper right tubular portion embracing the post, a lower tubular portion having a downwardly outwardly inclined inner surface, and a transition portion between the upper and lower portions. The top shelf, which is mountable in the region of the tops of the posts, is formed with four blind tubular collars, each having a downwardly outwardly inclined inner surface and an inwardly projecting retaining flange at the bottom edge of the surface.