Abstract: Objective: To investigate the expression of the RECK gene in the human breast (cancer) cell lines and to determine the relationship between the expression level of RECK gene and invasive capacity of the breast cancer cell lines. Methods: The invasive capacity of breast (cancer) cell lines, including HBL-100, MCF-7 and MDA-MB-435S, were determined by Transwell method. The protein expressive levels of RECK, MMP-2 and MMP-9 gene in these three cell lines were measured by immunocytochemical method. And the expressions of RECK in gene and protein level were measured by Western Bloting and RT-PCR technique in breast (cancer) cell lines respectively. Results: The invasive capacity of breast (cancer) cell lines was as follows: the MDA-MB-435S was the highest (425.20±54.09), the MCF-7 the moderate (239.00±91.39) and the HBL-100 (101.00±63.88) the lowest. There were significant differences in the invasive capacity among the 3 groups (P<0.01). The protein expression level of RECK gene in HBL-100 cell line was high (IC: 3188.24±894.86; WB: 3.32±0.25), but no expression was found in MDA-MB-435S cell line. The value of MCF-7 was as follows, i.e. IC: 1058.92±336.53, (P<0.01) and WB: 2.23±0.59, (P<0.05). Moreover, the expression of RECK gene was negatively correlated with that of the MMP-2, MMP-9 gene. The mRNA level of RECK gene in the HBL-100 cell line was the highest (2.32±0.02), and no expression of the RECK was found in the MDA-MB-435S cell line (P<0.001). Conclusion: There was a significant negative correlation between the expressive level of RECK gene and the invasive capacity in vitro as well as expressive level of the MMP-2, MMP-9 gene.