Diagnosis of choledocholithiasis is diffi cult because a clinical evaluation and blood tests are frequently insuffi - cient for an exact diagnosis of choledocholithiasis. Patients often undergo ERCP which may be unnecessary but which generate high rates of morbidity and mortality. For this reason we decided to undertake this study to determine if the use of laboratory exams can predict choledocholithiasis to guide the decision to perform therapeutic ERCP. Patients and Methods: For this cross sectional observational study we chose a study population of all elderly patients who were undergoing ERCP on suspicion of choledocholithiasis. Logistic regression analysis was used to establish the degree of association between predictive variables. Choledocholithiasis diagnosed by ERCP was our independent variable while the dependent variables were age, gender, jaundice, pain, presence of cholelithiasis diagnosed ultrasound, presence of choledocholithiasis diagnosed ultrasound, total bilirubin count, direct bilirubin count, of direct bilirubin count over 30% of total bilirubin, AST, ALT, and alkaline phosphatase. We obtain the odds ratios (ORs) for prevalence. Our model for multivariate analysis took into account those values that were statistically signifi cant in the construction of 2x2 tables. Results: Of the 120 patients included in the study, 84 were women (70%). The average age was 58 years, and patients' ages ranged from 18 to 75 years. Choledocholithiasis was found in 83 patients (69.17%), dilated bile ducts in 84 (70%). The presence of dilatation and/or gallstones was found in 96 patients (80%). The bivariate analysis found that age (> 55 years), jaundice, elevated total bilirubin, elevated direct bilirubin, ALT 2, AST 2 and direct bilirubin greater than 30% of total bilirubin had statistical signifi cance due to their relation to dilation of the common bile duct diagnosed by ERCP. Multivariate logistic regression of these factors found that people over 55 years of age are 5.19 times more likely to be diagnosed with choledocholithiasis by ERCP than younger patients, patients with elevated direct bilirubin are 4.98 times more likely to be diagnosed with choledocholithiasis by ERCP than patients without elevated direct bilirubin, and patients with direct bilirubin greater than 30% of total bilirubin are 9.73 times more likely to be diagnosed with choledocholithiasis by ERCP than patients with lower ratios. These three factors were the only independent predictors of choledocholithia- sis diagnosed by ERCP found in the multivariate logistic regression. Conclusion: Based on the fi ndings of this study we conclude that for patients with cholelithiasis direct bilirubin greater than 30% of total bilirubin indicates a probability 9.7 times greater for choledocholithiasis than for patients with a lower ratio, and 43 times greater that they will have a positive ERPC fi nding for choledocho- lithiasis and/or a dilated bile duct. The probability increases further if the patient is older than 55 years with the odds ratio reaching 11.3. In these cases performance of ERCP is indicated.