Background and purpose: Colorectal cancer (CRC) is a malignancy which is the third incidence and the fourth mortality in the worldwide. The main reason for the development of CRC is that the changes of genetic and epigenetic causes the tumor suppressor gene methylation silencing. This study aimed to investigate the plasma and stool GATA5 gene promoter methylation was detected in clinical diagnosis of CRC. Methods: To collect the paired plasma and stool specimens of 34 cases of healthy and 43 cases of patients with CRC. Methylation specific PCR (MSP) was respectively detected the GATA5 gene methylation levels of GATA5 gene in plasma and stool. And then separately analyzed their correlations with clinical and pathological parameters in gastric carcinoma. Results: The result of MSP showed that GATA5 gene promoter methylation rates in plasma and stool of CRC patients were 60.74%

76.60%

respectively

were higher than those of healthy persons (6.47%

32.35%). And the differences were statistically significant (P=0.006 7

P=0.000 2

respectively). GATA5 gene methylation rates in plasma of CRC patients were closely related to clinical stage (P=0.000 5) and lymph node metastasis(P=0.020)

while GATA5 gene methylation rates in stool of CRC patients had no significant with clinical and pathological parameters. Conclusion: Detection of faecal GATA5 gene methylation level and supplemented plasma GATA5 gene methylation level can become a simple

non-invasive

sensitive and specific method for clinical diagnosis of CRC.