Abstract: ObjectiveTo investigate the correlation between the expression of excision repair cross-complementing gene 1（ERCC1）in paraffin tumor tissue and corresponding blood cells of lung，colon，gastric and breast cancer patients. Methods Real-time quantitative PCR was used to detect ERCC1 mRNA expression of 230 lung cancer，160 colon cancer，125 gastric cancer and 100 breast cancer cases from paraffin tumor tissues and corresponding peripheral venous blood samples. Results There was no significant difference in ERCC1 mRNA expression of tumor tissues and peripheral blood among the four types of cancers（P＞0.05）. The expression of ERCC1 in tumor paraffin tissues of lung，colon，gastric and breast cancer were much higher than that in corresponding peripheral blood（P＜0.05）. There was a positive correlation between the expression of ERCC1 mRNA in peripheral blood and cancer tissues（lung cancer：r=0.430，P＜0.001；colon cancer：r=0.553，P＜0.001；gastric cancer：r=0.583，P＜0.001；breast cancer：r=0.501，P＜0.001）. There was no relation between the ERCC1 expression and the clinical characteristics including age and gender in tumor tissues and peripheral blood of lung, colon and breast cancer. The expression of ERCC1 mRNA in tumor tissue and peripheral blood had no correlation with age in gastric cancer, but it had higher expression in male than in female in tumor tissues. Conclusion The expression levels of ERCC1 mRNA in peripheral blood can indirectly reflect their expression levels in lung，colon，gastric and breast cancer tissues.