Combined 2-dimensional and M-mode echocardiography was used to assess the cardiac status of 22 patients with Friedreich's ataxia, and the findings were correlated with the clinical and electrocardiographic (ECG) data. Mean age at onset of Friedreich's ataxia was 8 years (range 3 to 18); mean age at echocardiography was 18 years (range 8 to 39). Echocardiographic findings were abnormal in 19 patients (86%). The 3 patients with normal echocardiographic findings did not have cardiac symptoms, but 1 had ECG repolarization abnormalities. Concentric left ventricular (LV) thickening, the most common echocardiographic finding, was found in 15 patients (68%) and in all 15 the papillary muscles were thickened. These 15 patients had ECG repolarization abnormalities and 5 had left-axis deviation; however, only 3 satisfied ECG criteria for LV or right ventricular hypertrophy. Two of the 15 patients (9%) had symptoms of heart failure. Two patients had asymmetric septal thickening without clinical evidence of LV outflow tract obstruction; neither had cardiac symptoms, but both had ECG repolarization abnormalities. Two patients showed a dilated cardiomyopathy pattern; both had heart failure and atrial flutter. One of these patients died, and necropsy revealed 4-chamber cardiac dilatation, biventricular hypertrophy and histologic findings of diffuse interstitial fibrosis, myocellular hypertrophy and necrosis. This study revealed a wide spectrum of cardiac abnormalities in patients with Friedreich's ataxia.