The author expounds a new concept of pathogenesis of gallbladder cholesterosis formulated based on the results of morphological studies of a large number of gallbladders obtained after cholecystectomy with the use of modern methods of light and electron microscopy and immunohistochemcal techniques. The totally new data on the structure of the gallbladder wall and its pathomorphosis in the course of development of the disease are presented. The newly discovered phenomenon of the absorption of  bile micelles by absorptive epitheliocytes via endocytosis and their penetration into lamina propria is described. It is hypothesized that this process triggers the  activation of histiocytes and their transformation into tissue macrophages. Immunohistochemical investigations have demonstrated for the first time that macrophages serve as the sole phenotypic precursors of foam cells. It is concluded that the general derangement of lipid metabolism and the accompanying changes in the synthetic and secretory functions of hepatocytes play the role of the etiological factors underlying gallbladder cholesterosis. The authors maintain that cholesterosis and cholecystolithiasis represent different stages of the single pathology rather that different diseases.