The intrarenal renin-angiotensin system and reactive oxygen species contribute to the progression of chronic kidney disease. Godin et al. applied transgenic methods to prove renoprotection by catalase. They show that all of the pathological effects of overexpression of angiotensinogen can be attributed to stimulation of hydrogen peroxide pathways. This indicates a protective role for catalase and underscores the importance of the intrarenal renin-angiotensin system in renal disease.