We evaluated the usefulness of percutaneous biopsy under sonographic control and histological examination in the early diagnosis of hepatocellular carcinoma (HCC) in comparison with CT and angiography. 121 patients in whom hepatic nodules 3cm or smaller in size were found by ultrasound as suspected HCC underwent percutaneous biopsy, CT and angiography. 118 patients were finally diagnosed as HCC. Correct diagnosis of HCC was obtained by each modality in relation to tumor size as follows: 87.3% by histological examination, 55.1% by CT, 52.5% by angiography. However, the diagnostic capability of these modalities for HCC 1.5cm or smaller in size was as follows: 88.5% by histological examination, 34.6% by CT, and 23.1% by angiography. Cytology using a biopsy specimen was performed in 26 patients and it showed a positivity of 61.5%. In conclusion, for a definitive diagnosis of small HCC 1.5cm or less in size, the current imaging modalities have some limitations. On the other hand, percutaneous biopsy and histological examination are the most reliable and indispensable for making a definite diagnosis of small HCC.