Abstract: An improved modular type safety deposit box system. In preferred form, each module is comprised of the same basic casing structure, and an initially separate door frame structure, these two components then being assembled into a completed module after pre-assembly of each component. Each module's casing may be subdivided into more than one compartment by use of a plurality of standardized horizontal dividers and, if desired, standardized vertical dividers, the dividers being arranged as desired in operative engagement with the casing through a slot and tab structure. Each module's door frame is comprised of a hoop-shaped frame adapted to be subdivided into a plurality of access ports corresponding to the same number of compartments provided in the basic casing. The doors for each access port of the frame may be installed to hinge from one side of the frame if no vertical dividers are used in the casing, or from a center hinge post fixed in the frame if vertical dividers are used in the casing.