We performed a prospective study to determine the prevalence of cholelithiasis in patients with abdominal aortic aneurysm. Over an 18-month period, the gallbladder and the abdominal aorta were evaluated routinely in all consecutive patients referred to us for sonography of the abdomen and retroperitoneum. The patients were divided into two groups: those with an abdominal aortic aneurysm (aorta greater than 3 cm in transverse diameter) (n = 96) and those whose aorta measured less than 3 cm in transverse diameter (n = 538), who served as control subjects. Cholelithiasis was found in 50% of patients with and 26% of patients without aneurysm (p less than .0001). A stepwise logistic regression analysis found age alone to be predictive of cholelithiasis (p = .030). However, age was not predictive of cholelithiasis when included with abdominal aortic aneurysm in a multivariate model. Diabetes mellitus and gender were not predictive of cholelithiasis. We found cholelithiasis in approximately half of the patients who had abdominal aortic aneurysms. This is almost double the prevalence in the general elderly population. A pathophysiologic explanation for this observation remains to be found.