The invention relates to a method for three-dimensional localization of an instrument for an interventional access, comprising: creating a three-dimensional image recording covering a region of the intervention and surroundings; determining local attenuation values of the three-dimensional image recording by x-ray absorption characteristics; recording a two-dimensional image recording covering the region of the intervention and surroundings; determining an x-ray intensity at an x-ray sensor arranged on the instrument; localizing the x-ray sensor in the two-dimensional image recording based on the x-ray intensity; summing the local attenuation values along a virtual x-ray path passing through the x-ray sensor in the three-dimensional image recording; identifying a point on the virtual x-ray path where the attenuation sum corresponds to the x-ray intensity at the x-ray sensor; and determining a three-dimensional position of the point corresponding to the three-dimensional position of the x-ray sensor on the instrument.