The oldest old are the fastest growing component of many national populations. No large-scale analysis of electrocardiographic findings in this group exists to date. This study cataloged the frequencies of specific electrocardiographic (ECG) findings in the target population and compared the frequencies of these findings by gender and race. The electrocardiograms of 888 subjects aged > or =90 years presenting for any reason were retrospectively analyzed using standard criteria for 128 separate ECG findings. Left ventricular enlargement (28%), first-degree atrioventricular block (16%), and atrial fibrillation (15%) were the most common abnormalities found in the population as a whole. In contrast to previous studies, which demonstrated a predominance of left-axis deviation, 91% of the electrocardiograms analyzed in our study demonstrated a mean frontal QRS axis ranging from -30 degrees to +90 degrees . Sinus rhythm was observed in 79% of the population. More Caucasians than African-Americans had atrial fibrillation (19% vs 12%, p = 0.004). Women had more normal ECG results than men (6% vs 2%, p = 0.02), and more women demonstrated complete right bundle branch block (13% vs 7%, p = 0.002). In conclusion, few patients aged > or =90 years who have their electrocardiograms recorded at hospitals have completely normal ECG results. The frequencies of some ECG findings in the target population vary by gender and race.