A method of filling a pressure medium accumulator with a housing having an inner space that is subdivided into two chambers by a metallic pleated bellows used as a media-separating element. The first chamber thereof is filled with a gas and the second chamber is filled with a liquid pressure medium. The bottom valve is provided in a hydraulic port, its closing member being operable by the media-separating element. The valve permits filling of the second chamber with fluid and prevents a complete evacuation of the second chamber. To enable reliable filling of the above-mentioned chambers with corresponding media without damaging the pleated bellows, the method includes the steps of evacuating the second chamber, filling the second chamber with pressure medium and filling the first chamber with a gas.