The carcinogenesis mechanism of human salivary gland adenocarcinoma NOS is poorly understood. MicroRNA155(miRNA155) has been involved in the carcinogenesis of many malignant tumors. The purpose of this study was to examine the role of miRNA155 in tumor growth and invasion of adenocarcinoma NOS. Using SGT cells as a model for adenocarcinoma NOS, cell proliferation was examined by MTT assay after knocking down miRNA155 expression, and cell cycle analysis was performed. Invasive capacity by a Transwell culture assay, and miRNA155 expression in SGT cell line by RT-PCR were examined. In MTT assay, proliferation of SGT-miRNA155 cells was decreased prominently after 96 hrs. Proliferation of SGT cells was markedly inhibited by knocking down miRNA155, resulting from a blockade of cell cycle in the G1 phase, but apoptosis was increased about 4 folds. In adhesion assay, SGT-miRNA155 cells decreased about 60% compared to SGT cells. In invasion assay, inhibition of miRNA155 significantly suppressed the invasive capacity of about 34% SGT cells. mRNA expression of SGT-miRNA155 cells prominently were decreased compared to SGT cells by RT-PCR. It suggested that miRNA155 could play an role in cell cycle progression and invasion in SGT cells, including antitumor effect. These results have provided insights into the carcinogenic mechanisms and new intervention method of salivary gland adenocarcinoma NOS.