Objective:To study the expresion and significance of CXCR4 in gastric cancer (GC) and intra-abdominal metastasis.
Methods:Immunohistochemistry and PT-PCR were used to detecte the expresion of CXCR4  protein and CXCR4 mRNA in GC, lynph node metastasis (LNM), peritoneal metastasis (PM) and normal stomach (NM) tissues.
Results:There was no CXCR4 expression in normal gastric mucosa cell.The expression rate of CXCR4 in GC and PM was 59.4%,100% respectively（P＜0.05）. The expression of CXCR4 in primary tumor was correlated with tumor stage,depth of tumor invasion and lymph node metastasis(P＜0.05), but not with age,gender,location of tumor, tumor size and pathological differentiation of patients (P＜0.05). (2)Semi-quantatitive RT-PCR analysis showed that there was no CXCR4 mRNA expression in normal gastric mucosa. Low quantity of CXCR4 mRNA was detected in 5 early cancer samples, high quantity of CXCR4 mRNA was detected in specimens of all advanced cancer tissue; the quantity of CXCR4 mRNA in LNM and PM was the highest （P＜0.05）.  
Conclusions:CXCR4 is expressed in both primary and metastic lesion in gastric cancer.Moreover, CXCR4 is upregulated when the tumor cell metastasize to lymph node and peritoneum.  CXCR4 expression in primary tumor is correlated with tumor stage, invasion depth,  LNM and PM. As the cancer progress, the expression of CXCR4 is upregulated, which implies that tumor cell with high expression of CXCR4 have more aggressive and metastatic capacity.