Abstract: A modular roller mat for providing rolling movement of cargo units over the floor of a cargo deck. The roller mat comprises a plurality of interconnected roller tray assemblies. Each roller tray assembly comprises a tray and a plurality of modular roller assemblies including a housing and a roller unit. The tray includes a floor, a first side wall, a second side wall and a flange extending inwardly from each side wall. The housing includes a plate and a downwardly extending collar. The plate extends between the side walls of the tray and is removably attached to the flanges of the tray. The collar includes an annular sleeve through which the roller unit is inserted. The roller unit includes a rotatable retainer member. Once inserted, the roller unit retainer is rotated such that retaining lugs on the roller unit retainer engage the sleeve to retain the roller unit in the housing. The roller assemblies are easily removed and replaced in the tray and are interchangeable with one another.