Human cyclin D3 gene (CCND3) located on 6p21.1 is important for the regulation of the G1-S phase transition of the cell cycle by modulating the activity of the cyclin-dependent kinases Cdk4 and Cdk6. Because little is known about the effect of cyclin D3 in various human cancers, we evaluated the intricate relationship between expression of cyclin D3 and the process of HCC development using immunohis tochemistry and TUNEL assay on 43 paraffin embedded tissues. Cyclin D3 immunoreactivity was more frequently observed in the tumors with high histologic grade and the tumors with metastasis, and more frequently expressed in HCCs with cirrhotic background and gain of 6p21.1 when compared with those with non-neoplastic tissue. Apoptotic cells were more common in tumor with cirrhotic background, amplification of 6p21.1 and expression of cyclin D3 when compared with HCCs with lower level of cyclin D3 expression. Also, we observed that some of the cyclin D3 positive cell and apoptotic cell were co-localized. From these results, it is suggested that over-expression of cyclin D3 may contribute to more rapid cell turn-over in the background of HCC, and balance between proliferation and apoptosis is a role in the progression of HCC with cirrhotic background.