5 patient with cholesterol gallstones were treated with cis-2-hydroxy-2-penyl-cyclohexanecarboxilic acid (cicloxilic acid) 240 mg daily for one year. Before treatment and after 1 month's, 3 months' and 1 year's treatment gallbladder bile was withdrawn by duodenal tube after i.v. cerulein stimulation. The bile was assayed for lipids and the lithogenic index was determined. The pool of bile acids was also determined and liver function tests performed. The results show a gradual lowering of the mean lithogenic index in the course of treatment. The blood chemistry values remained within strictly normal limits.