Two recent randomized trials pointed out the beneficial effect of enzyme replacement therapy on biochemical parameters in patients with Anderson-Fabry's disease. Clinical end-points, such as amelioration or stabilization of renal function deterioration, or improvement of left ventricular hypertrophy have not been evaluated in depth. We report the case of a patient whose moderately impaired renal function was stabilized with the start of enzyme treatment. In addition, left ventricular hypertrophy tended to regress. To our knowledge this is the first observation of clinical efficacy of the enzyme replacement therapy in Anderson-Fabry's disease in patients with moderately impaired renal function.