Left atrial dimensions were recorded echocardiographically in 50 patients with atrial fibrillation. Fibrillatory wave amplitude (f wave) was measured in lead V1 of standard electrocardiograms for all patients. Left atrial dimensions (LAD), LAD compared to body surface area (LAD/M2) and the ratio of LAD to aortic root diameter (LAD/AR) were calculated. There was no significant correlation between f wave size and LAD (p = 0.6480), between f wave size and LAD/M2 (p = .6721), or between f wave size and LAD/AR (p = .1157), nor was there any association between LAD and the etiology of the heart disease. F wave size did correlate (p = .0073) with the age of the patient, the older the individual, the more likely was he to have fine atrial fibrillation (peak to trough f wave less than 0.5 mm).