This report describes an open-label, nonrandomized, prospective evaluation of the effects of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker therapy on patients who have Fabry disease and also received enzyme replacement therapy with agalsidase-β, given at 1 mg/kg body wt every 2 wk. Previous placebo-controlled phase III and phase IV trials with agalsidase-β demonstrated clearing of globotriaosylceramide from vascular endothelia but little effect on proteinuria or progressive loss of kidney function in patients with Fabry disease and severe chronic kidney disease marked by overt proteinuria and/or estimated GFR <60 ml/min per 1.73 m2. Angiotensin-converting enzyme inhibitor and/or angiotensin receptor blocker therapy is the standard of care for patients with proteinuric kidney diseases, but their use is challenging in patients with Fabry disease and low or low-normal baseline systemic BP. A group of patients with Fabry disease were treated with antiproteinuric therapy, in conjunction with agalsidase-β; sustained reductions in proteinuria with stabilization of kidney function were achieved in a group of six patients who had severe Fabry nephropathy; the progression rate was -0.23 ± 1.12 ml/min per 1.73 m2 per yr with 30 mo of follow-up. Copyright © 2007 by the American Society of Nephrology.