Four hundred thirty-two middle-aged to elderly adults were examined by means of real-time ultrasonography as a mass screening method for liver and gallbladder diseases. Among them, 36 cases of diffuse liver disease and 22 cases of gallstones were detected. The results of the ultrasonic examinations were compared with the data obtained from blood laboratory examinations of hepatic function and lipid metabolism as well as with certain questionnaires on the history of such diseases, etc. Although some of the cases diagnosed as diffuse liver disease by ultrasonography showed abnormalities in the blood laboratory examinations, others showed normal data. Most of them were found to have a hsitory of liver disease, however. Ultrasonography revealed morphological changes in the liver due to chronic diffuse liver damage occurring in the inactive phase when blood laboratory data were normal. The significance of ultrasonic mass screening for liver disease lies its ability to reveal cases of morphologically changed livers whether they show abnormalities in blood laboratory examinations or not. As most cases of liver cancer have a hsitory of diffuse liver disease, it may be important to detect cases of diffuse liver disease by means of both ultrasonography and blood laboratory examination. Cases diagnosed as gallstones by ultrasonography did not have a definite tendency to show any abnormality in the blood laboratory examinations or have a history of gallbladder disease or clinical symptoms. Consequently, most of them could be designated as "silent gallstones" by ultrasonography, a very effective means of discovering them. As gallstones are suspected to be one of the decisive factors of gallbladder cancer, their early detection may be important in preventing it. Ultrasonic mass screening examinations are considered a reliable screening method for diffuse liver disease and gallstones.