We identified a novel lncRNA SNHG15, whose expression was upregulated in tumor tissues in 106 patients with gastric cancer (GC) compared with those in the adjacent normal tissues. Furthermore, increased SNHG15 expression was positively correlated with invasion depth, advanced tumor node metastasis (TNM) stage, and lymph node metastasis. SNHG15 levels were robust in differentiating GC tissues from controls. Kaplan-Meier analysis demonstrated that elevated SNHG15 expression contributed to poor overall survival and disease-free survival of patients. A multivariate survival analysis also indicated that SNHG15 could be an independent prognostic marker. Furthermore, knockdown of SNHG15 expression by siRNA could inhibit cell proliferation and invasion and induce apoptosis, while ectopic expression of SNHG15 promoted cell proliferation and invasion in GC cells partly via regulating MMP2 and MMP9 protein expression