Objective To study the significance of the expression of mitochondrial DNA Cyt-b and vascular endothelial growth factor mRNA in human breast cancer. Methods Reversedtranscription polymerase chain reaction（RT-PCR）was applied to detect the expressions of mtDNA Cyt-b and VEGF in 19 samples of breast cancer tissue and 19 samples of peritumoral tissues. β-actin served as a quantitative standard marker. The different expressions in breast cancer tissues and paracancerous tissues were compared and their relations with clinical pathology parameters were analyzed. Results The expressions of mtDNA Cyt-b and VEGF mRNA in 19 samples of breast cancer tissues were higher than those in paracancerous tissues, with a significant difference between the two groups (P<0.01). The expression of mtDNA Cyt-b was positively correlated with the expression of VEGF mRNA (P<0.01) and the expression of VEGF145 and VEGF189 mRNA (all P<0.05). The expression of VEGF145 and VEGF189 mRNA, which were the isomerides of VEGF, was higher in breast cancer tissues than in paracancerous tissues, with a difference between the two groups (P<0.05). The expression of mtDNA Cyt-b and VEGF mRNA in lymph node metastasis group was higher than that of nonlymph node metastasis group, with a difference between the two groups (P<0.05). The expressions of mtDNA Cyt-b and VEGF mRNA in phase Ⅰof TNM stage were lower than those in phase Ⅱ, with a difference between the two groups (P<0.05). There was a significant differe