Abstract: The aims of the present study were to evaluate the effects of puerarin on angiotensin Ⅱ-induced cardiac fibroblast proliferation and to explore the molecular mechanisms of action. Considering the role of H₂O₂ in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, we hypothesized that modulating catalase activity would be a potential target in regulating the re-dox-sensitive pathways. Our results showed that the activation of Rac1 was dependent on the levels of intracellular H₂O₂. Puerarin blocked the phosphorylation of extracellular regulated protein kinases (ERK)1/2, abolished activator protein (AP)-1 binding activity, and eventually attenuated cardiac fibroblast proliferation through the inhibition of H₂O₂-dependent Rac1 activation. Further studies revealed that angiotensin Ⅱ treatment resulted in decreased catalase protein expression and enzyme activity, which was disrupted by puerarin via the upregulation of catalase protein expression at the transcriptional level and the prolonged protein degradation. These findings indicated that the anti-proliferation mechanism of puerarin was mainly through blocking angiontensin Ⅱ-triggered downregulation of catalase expression and H₂O₂-dependent Rac1 activation.