Sonographic and histologic correlation was studied in 20 cases with a combined total of 23 resected lesions of hepatocellular carcinoma. All cases were examined by sonography within 1 week before surgery. Tumor sonograms were classified as hypoechoic, complex, or hyperechoic on the basis of the difference in echogenicity between the lesion and the surrounding liver parenchyma. Fourteen excised pathologic specimens were examined after surgery by a fixed-position sectional sonographic technique that permitted detailed comparison of the sonograms with the histologic findings. Each of the three types of lesion classified by echo pattern exhibited specific histopathologic characteristics. The hypoechoic lesion corresponded to a solid tumor without necrosis; the complex lesion corresponded to a tumor with partial necrosis; and the hyperechoic lesion was represented histopathologically by two distinct types of tumor, one with fatty metamorphosis and the other with marked sinusoidal dilatation. Fixed-position sectional sonography is a useful technique for comparing histologic and sonographic findings in a given tissue section and it contributes to the investigation of tissue characterization by sonography.