The value of ultrasound in the diagnosis of choledocholithiasis is controversial, sensitivity figures ranging from 22 to 75%. We correlated the ultrasound study with operative findings in 38 patients. A diagnosis of common bile duct stone was made upon finding an echogenic image with or without acoustic shadow in the common bile duct; no attention was paid to the dilatation of the biliary tree. The sensitivity was 68% and the positive predictive value was 85%. Therefore, our results approach the highest reported figures for the value of this diagnostic technique.