Abstract: Objective To explore the expression levels of long non-coding RNA H19 in tissues and cells of gastric cancer， and investigate the effect of H19 in cell proliforation of gastric cancer MGC-803 cell line. Methods Real-time quantitative PCR was applied to detect the expression of H19 in 30 paired tumor tissues and corresponding adjacent normal tissues， normal epithelial cell line GES-1 and gastric cancer MGC-803， SGC-7901 cell lines. The relationship between the expressions of H19 in tumor tissues with clinicopathological characteristics（age， gender， degree of differentiation， depth of tumor invasion， lymph node metastasis and TNM stage） was analyzed. The specific small interfering RNA for H19（si-H19 group） or negative control sequence（si-NC group） were transfected into MGC-803 cells. The MTT assay and clone formation experiment were employed to detect the proliferation of two groups. Results The levels of H19 in both gastric cancer tissues and cells were higher， compared with adjacent normal tissues and gastric epithelial cells. The expression of H19 was related with depth of tumor invasion， lymph node metastasis and TNM stage（P＜0.05）， but not with age， gender and degree of differentiation（P＞0.05）. Compared with si-NC group， there were lower H19 level, cell activity and cell clone number in si-H19 group with statistical significance（P＜0.05）. Conclusion There is high expression of H19 in gastric cancer tissues and cells. Down-regulating H19 expression can inhibit gastric cancer cell proliferation， which may participate in the occurrence and development of gastric cancer.