['Accurate sampling of gallbladder bile for biliary analysis is essential for determining any potential difference between combined bile acid therapy and monotherapy in gallstone patients.', 'In 104 gallstone patients undergoing extracorporeal shock wave lithotripsy with following bile acid therapy [either chenodeoxycholic acid (500 mg/day) and ursodeoxycholic acid (500 mg/day), group I (n = 53), or ursodeoxycholic acid alone (1000 mg/day), group II (n = 51)], bile samples, obtained by direct fine needle puncture of the gallbladder, were investigated for biliary lipids, total biliary protein concentration, and nucleation time before and after 12 months of bile acid therapy.', 'Initially, a negative correlation was found between nucleation time and number of gallstones and between total biliary protein concentration and nucleation time (r = -0.52 and r = -0.49 in group I vs r = -0.56 and r = -0.51 in group II, p < 0.01 in each group). The correlation between total biliary protein concentration and nucleation time was also found after 12 months of bile acid treatment (r = -0.54 in group I vs r = -0.47 in group II, p < 0.01 in each group). In group I, the decrease in cholesterol saturation index, biliary cholesterol, cholic acid, deoxycholic acid, and total protein concentration was more pronounced than in group II (p < 0.01). The same effect was found concerning the prolongation of nucleation time (p < 0.01). Furthermore, dissolution rates were higher in group I compared with group II (80.4 vs 69.0%, p < 0.01).'] Is combined bile acid therapy more effective on biliary lipids and dissolution rates than monotherapy after gallstone lithotripsy?