Fabry disease (FD) is an inherited deficiency of the lysosomal hydrolase alpha-galactosidase A (α-GalA).It is a rare X-linked recessive storage disease that causes the intralysosomal accumulation of glycosphingolipids, mainly globotriaosilceramide (GL-3), leading to a multisystemic disease characterized by  angiokeratoma, hypohidrosis, acroparesthesia and  ocular opacity. Due to the GL3 accumulation in vascular endothelium it also leads to end-stage renal disease, cardiac and cerebrovascular disease. In the absence of a family member who has already received a diagnosis of FD, many cases are not diagnosed until adulthood, making FD an under diagnosed disease. The screening among dialysis patients is important because it possibilities the detection of FD on their family members and also assure the correct treatment with the enzyme reposition therapy. The aim of this work was to establish a normality curve of the enzyme activity values in a control group as well as to find patients with FD among dialysis patients. The control curve demonstrates the normal enzyme activity values in our population and from these results we can establish the value that is compatible with FD. We determined the α-GalA activity of 120 healthy men and 1204 male dialysis patients from dried blood spots samples on filter paper using a fluorescence assay (Chamoles et al, 2001). The mean value of α-GalA activity in the control group was 4.6 µmol/L/h, following a normal distribution (Kolmogorov-Smirnov test, p>0,20). The mean value in the dialysis group was 6.83 µmol/L/h (Kolmogorov-Smirnov test, p<0,01), not following a normal distribution mainly due to the heterogeneity of the group which included people with different types of renal disease. We have identified until now 11 values compatible with FD among dialysis patients. A new sample of blood, to confirm the result in leukocytes, were required to patients with results lower than 2µmol/L/h.The value considered compatible with FD in leukocytes was under 1.4 µmol/L/h.