The occurrence rate of diabetes was analyzed in 3370 consecutive patients admitted and surgically treated for biliary lithiasis at the I Department of Surgery-University of Rome "La Sapienza"-between 1959 and 1993. The incidence of such association was found to be overlapping with that of normal population. The natural history and the outcome of patients surgically treated for biliary lithiasis do not seem to be burdened by a concurrent diabetes. Diabetes was in turn found to be correlated with a more frequent presence of stones in the biliary tract. Possible causes of this correlation are discussed. The need in these patients of a more accurate diagnostic approach and specific therapeutic solutions is stressed.