patients prefer the quick and definitive answer of an operation, whereas others are unable to accept the necessary time off work, are afraid of surgical treatment, or prefer to avoid a scar for cosmetic reasons. Many are grateful to have the option of safe, pain free oral treatment in the form of bile acids.While the authors point out that treatment to dissolve gall stones has a failure rate of 50%, they fail to indicate that the efficacy is much higher when appropriate patients are selected. Maton et al achieved a dissolution rate of 80% by limiting treatment to those with gall stones of < 15 mm in diameter and by using a dose of chenodeoxycholic acid that results in desaturation of gall bladder bile (> 13 mg/kg) for 12 months.2 The dissolution rate is higher if computed tomography is used to exclude patients with small amounts of calcification not detectable by conventional radiology. The time when bile acids are given and the type of bile acids used are also important. Giving bile acids at bedtime is more effective than giving them at mealtimes.' A combination of chenodeoxycholic acid and ursodeoxycholic acid is more effective than monotreatment.4We agree that the rate of recurrence of gall stones can be as high as 50%, but, using an actuarial method based on lifetable analysis, we have shown that recurrence plateaus from the fifth year.' We believe that giving bile acids intermittently is probably the best long term strategy for preventing recurrence.