Effectiveness of periodic checkup by ultrasonography for the early diagnosis of hepatocellular carcinoma. Periodic checkup by ultrasonography was conducted on patients with chronic liver diseases for early detection of hepatocellular carcinoma. In 19 months, a total of 2004 examinations were performed on a total of 660 cases (179 cases with liver cirrhosis in the compensatory stage, younger than 70 years; 481 cases with chronic hepatitis, aged 40 to 70 years for men and 50 to 70 years for women). Of the 660 cases, 22 HCC cases (3.3%) were detected and finally diagnosed by angiography and/or histologic examination. Four of those cases (18%) had a single nodule smaller than 1 cm in diameter, and 11 cases (50%) had a single nodule smaller than 2 cm. Surgical resection was performed on 12 cases (55%). In comparison with the control group (83 HCC cases not receiving any periodic checkup), the frequency of small liver cancer and the surgical resection rate in the study group were significantly higher. This examination system by periodic ultrasonography checkup of patients with chronic hepatic diseases was effective for early detection and permitted aggressive therapy of hepatocellular carcinoma. 