Abstract: An improved medical restraining board for temporarily restraining, for example, a patient's forearm and wrist during intravenous administration of fluids. The arm board includes an elongated flat rigid support member which is padded on at least one side with a substantially flat sheet of flexible material having a plurality of spaced enclosed gas-filled pockets formed therein. The support member and padding are enclosed within an outer cover formed from a porous hydrophobic material, preferably of porous spun-bonded polyethylene fibers. In a modified embodiment, the support member and padding are enclosed within a microporous sealed inner cover and the outer cover is disposable and has a moisture-absorbent lining.