Military surplus are goods, usually matériel, that are sold or otherwise disposed of when held in excess or are no longer needed by the military. Entrepreneurs often buy these goods and resell them at surplus stores. Usually the goods sold by the military are clothing, equipment, and tools of a nature that is generally useful to the civilian population, as well as embroidered patches, name tags, and other items that can be used for a faux military uniform. Occasionally, vehicles (jeeps, trucks, etc.) will be sold as well. Some military surplus dealers also sell military surplus firearms, spare parts, and ammunition alongside surplus uniforms and equipment.

Demand for such items comes from various collectors, outdoorsmen, adventurers, hunters, survivalists, and players of airsoft and paintball, as well as others seeking high quality, sturdy, military issue garb. The goods may be used, or not. Some merchants of surplus goods also sell goods that are privately manufactured in military standards.

Most items that are sold in military surplus stores in the United States are deemed "military grade". This designation refers to meeting a relevant United States Military Standard. For example, uniforms meet Army Regulation 670-1.