L-type amino-acid transporter 1 (LAT-1) is a member of system L-type transporters, essential for cells maintenance and proliferation. However, the role of LAT-1 remains illegible in gastric cancer (GC). In this study, we found that LAT-1 was aberrantly up-regulated in both GC cell lines (MKN-45, MGC-803 and CRL-5974) and human GC specimens. The expression characteristic of LAT-1 in GC was significantly associated with clinicopathologic features such as tumor size, lymph node metastasis, local invasion and TNM stage. By suppressing the expression of LAT-1 in MKN-45 cells, the cell cycle was arrested in G0/G1 phase, and the ability of cell proliferation was significantly decreased in vitro. Moreover, the cell migration and invasion of MKN-45 cells was significantly impaired by knocking down LAT-1. Thus, our results suggest that LAT-1 may function as an oncogene in GC, which provides us a new biomarker in GC and perhaps a potential target for GC prevention, diagnose and therapeutic treatment.