This study aimed to develop a new set of screening criteria that is easily applicable and highly sensitive for the detection of patients at high risk of Fabry disease (FD) among hypertrophic cardiomyopathy (HCM) patients. We prospectively studied 273 consecutive unrelated patients who were referred to HCM clinic for unknown left ventricular hypertrophy. Among the 273 patients, we selected 65 high-risk patients who fulfilled at least one of our newly proposed screening criteria. All 273 patients were assayed for plasma α-galactosidase A (α-GAL A) activity. The new screening criteria were: (1) atypical HCM, (2) history or presence of documented arrhythmia, (3) short PR interval defined as <120?ms on electrocardiogram, and (4) symptoms of autonomic dysfunction. From this screening study, three unrelated patients (4.6%; 2 females and 1 male) were newly diagnosed with FD using α-GAL A activity and mutation analysis of the GLA gene. Using the screening method based on the newly proposed criteria, the prevalence of FD in our HCM population was 4.6% if at least one criterion was met and 18.8% if ?3 criteria were met. Therefore, our proposed criteria are easily applicable and highly sensitive for classifying patients at high risk of FD from HCM patients.