Success or failure of an attempted dissolution of gallstones depends--among other factors--on the nature, the quantity and the distribution of the different components. This paper presents an investigation of the distribution of the various components by X-ray microradiography. Due to their different absorption behaviour the following three classes of components could be distinguished: I. Components with low absorption: Cholesterol, II. Components with moderate absorption: Calcium palmitate monohydrate, calcium bilirubinate, III. Components with high absorption: Vaterite, aragonite, calcite, carbonate apatite. The distribution patterns of these classes of components showed that in all probability 12 out of the 27 gallstones which were examined would have resisted a dissolution.