We performed trend analyses between the lengths of DNA copy number (CN) segments and corresponding gene expression profiles from microarray data in hepatocellular carcinoma (HCC) and colorectal carcinoma (CRC). Significant correlations were observed in CN gain of HCC and CRC (p>0.05). The trend of the CN loss showed a significant correlation in HCC whereas there was no correlation between the length of CN loss segments and gene expression in CRC. Our findings suggest that the influence of CN on gene expression highly depends on the length of CN region, especially in the case of CN gain. To the best of our knowledge, this is the first study describing the correlation between lengths of CN alteration segments and expression profiles of corresponding genes.