Objective To investigate the effect of small interfering RNA of lactate dehydrogenase A (siLDHA) on migration and invasion of epidermal growth factor receptor 2 (ErbB2) over expressing breast cancer cell line SK-BR-3, MDA-MB-453 and its molecular mechanism. Methods SK-BR-3 and MDA-MB-453 cells were transfected with siLDHA to interfere with the expression of LDHA. The transfection of scramble siRNA was used as negative control. The LDHA protein levels were detected by Western blot ( PLDHA downregulated LDHA protein levels in SK-BR-3 and MDA-MB-453 cells ( PLDHA significantly decreased migration and invasion of SK-BR-3 and MDA-MB-453 cells ( PLDHA reduced LDH activity in SK-BR-3 cells, glucose uptake and lactate production in SK-BR-3 and MDA-MB-453 cells, the difference was significant ( P