Abstract: Objective: To study the relationships between Helicobacter pylori L-form (Hp-L)infection and the invasion and metastasis of gastric carcinoma BGC-823 cells.Further to explore the probable mechanism between Hp-L infection and the progression of gastric carcinoma.Methods: Hp were incubated and induced into Hp-L.Then gastric cancer BGC-823 cells were co-incubated with them for 24 hours in different ratio and a control group was set.The ability of invasion and metastasis of BGC-823 cells were evaluated by using Transwell chambers.The expression of ezrin in BGC-823 cells was assessed by Western-blotting.Results: With the increasing of the concentrations of Hp-L forms,the cells which permeated the membrane were increased (P<0.05 to P<0.01),and the expression of ezrin in gastric carcinoma BGC-823 cells was risen (P<0.01).Conclusions: The infection of Hp-L form can increase the invasion and metastasis ability of gastric carcinoma cells.The mechanism may have relationship with the over-expression of ezrin.