BACKGROUND AND AIMS: Electrocardiographic (ECG) abnormalities are often found in older patients but relatively few epidemiological studies have been performed. This study describes: a) cross-sectional differences in ECG abnormalities among three 70-year-old cohorts born over a period of 30 years; b) longitudinal changes in ECG abnormalities from the age of 70 to 85; and c) the relationship between ECG abnormalities at age 70 and subsequent 10- and 15-year mortality in men and women. METHODS: Trends in the prevalence of ECG abnormalities were investigated among 2100 70-year olds (994 men, 1106 women) from three cohorts born in 1901/02 (I), 1911/12 (III) and 1930 (VI). Longitudinal changes and mortality risks were investigated among 973 70-year olds (449 men and 524 women) from cohort I, which was followed from 1971 until 2001. RESULTS: In both sexes, the prevalence of ECG abnormalities was significantly lower in the later-born cohorts. From age 70 to 85, there was an increase in both men and women of large or intermediate Q-waves, left axis deviation, negative T-waves (0-5 mm), complete right bundle branch block (RBBB), and atrial fibrillation or flutter. Compared with those with no ECG abnormalities, the mortality risk was higher among individuals with large and intermediate Q-waves and negative T-waves (> or = 1 mm) in both sexes, and STJ depression > or = 0.5 mm and complete LBBB together with complete RBBB and intraventricular block; QRS > or = 0.12 sec in men only. CONCLUSIONS: ECG abnormalities are frequent in the elderly, they increase with age, and are associated with increased mortality.