Results: The mean period between USG and spiral CT was 3.04±5.70 days. The diagnostic accuracy rate to HCC was 84.4%(103/122). There was no interobserver variation. In analysis of associated factors, there was no statistical significance in age, gender, cause(HBV, HCV, alcohol), stage(modified UICC), Child-Pugh Grade, cirrhosis, portal vein thrombosis, diffuse type of HCC, regenerative nodules(RNs) (P > 0.05). There was statistical correlation in the tumor size less than 2 cm, the solitary tumor and location at segement 8. (P > 0.05). Conclusion: Tumor size less than 2 cm, solitary lesion and location at segment 8 are significant factors to miss HCCs in USG diagnosis.