On the basis of oral cholecystography (OCG), we selected gallstone patients for nontoperative intervention. Their gallbladder function was considered as normal when gallbladder contracted over 50%-75% after a fat meal at 1 hour. We collected 99 gallstone patients and 19 normal controls; gallbladder function was normal in 77 patients and poor in 22. After a fat meal gallbladder volumes were calculated by B ultrasonography. The results showed that both fasting and residual volume in patients with so-called normal contraction were significantly greater than that in the controls (P < 0.001), though the contraction rate was not different. The combination of gallbladder contraction rate measurement and residual volume calculation by ultrasonography was superior over traditional OCG.