THE CAUSE of gallstone formation has not yet been clarified, but many theories have been proposed and discussed in surveys.1-5 Most gallstones consist mainly of cholesterol. In smaller and variable quantities, bile pigments, salts, protein, and fat also occur.4 All gallstones are principally built up in the same way.6 The bile salts and phospholipids are of importance for the solubility of the cholesterol in the bile. This role of the bile salts has long been known, while the contribution of the phospholipids in this connection was demonstrated and presented by Isaksson7 and Johnston and Nakayama.8 Variation in the balance of these cholesterol-dissolving components and cholesterol towards a preponderance of the latter can be said to be of major importance for the occurrence of gallstone. The most commonly discussed factors causing these changes are infection and inflammation, metabolic disturbances, and bile stasis. It has long been