Abstract: Objective To investigate the effects of shRNA-mediated silencing of integrin α9(ITGA9) expression on growth and lung metastasis of B16F1 melanoma cells. Methods ITGA9-shRNA plasmid was used to inhibit the expression of ITGA9 in melanoma cell line B16F1. The effectiveness and feasibility of RNA interference were confirmed by RT-PCR and Western blot. Subcutaneous tumor model and lung metastasis model were successfully established on C57BL/6 mouse for observation of tumor growth and the number of lung metastatic foci. Results Tumor growth was slowed down in ITGA9-shRNA(P<0.05).The ratio of average tumor volume between shRNA group and scramble-shRNA group was decreased by 36%. The number of lung metastatic foci was signifi cantly decreased(P<0.05). Conclusion Down-regulation of ITGA9 could inhibit B16F1 growth and lung metastasis in vivo. ITGA9 may be a promising target of gene therapy for melanoma.