Friedreich's ataxia has been associated with cardiac abnormalities similar to those seen in hypertrophic cardiomyopathy. To determine the presence of asymmetric septal hypertrophy and resting functional left ventricular outflow tract obstruction, 24 patients with Friedreich's ataxia and 14 asymptomatic first degree relatives were studied by echocardiography. The findings indicated that cardiac involvement in this disease is: 1) characterized by concentric, and not asymmetric, left ventricular wall thickening, 2) is genetically linked with the neurologic abnormality, and 3) is not commonly associated with resting, functional left ventricular outflow tract obstruction.