Abstract: AIM:To evaluate the injury caused by low concentration hydrogen peroxide (H2O2) in primary left atrial cells and the protective effect of piperine in rabbits. METHODS: Eighteen rabbits were randomly divided into three groups: normal control (NC) group, H2O2 group and piperine group. Left atrial cells were primarily cultured. In H2O2 group, 100 μmol/L H2O2 was added into culture medium for 2 hours. In piperine group, 7×10-6 mol/L piperine was added for 1 hour and then 100 μmol/L H2O2 was added for 2 hours. The parameters of oxidation and antioxidation were measured. RESULTS: In H2O2 group, cell viability, activity of superoxide dismutase (SOD) and content of glutathione hormone (GSH) decreased (P<0.05). But content of malondialdehyd (MDA), intracellular free calcium concentration and expression of mitochondrial mRNA increased obviously (P<0.05). Compared with those in the H2O2 group, these parameters improved significantly (P<0.05) in the piperine group. CONCLUSIONS: Piperine protects the oxidative stress induced by H2O2 in rabbit primary left atrial cells.