Abstract: A device for manually crimping metal caps of the type commonly used for medical solution bottles. The crimper takes the form of a generally cylindrical body dimensioned to be held in the hand and defining a cavity open at its bottom and along a portion of its side to receive the neck of a bottle upon which an uncrimped metal cap has been placed. A shoulder within the cavity bears against the skirt of the cap and, as the crimper is rotated relative to the bottle, the bottom of the skirt is turned inwardly to secure the protective cap upon the bottle neck.