Because global T wave inversion has not been specifically characterized, 100 electrocardiograms (ECGs) with this pattern (frontal plane T vector -100 degrees to -170 degrees with precordial T inversion) were prospectively collected from approximately 30,000 consecutively interpreted ECGs and analyzed blindly. There was a striking female predominance (82 women vs. 18 men; p less than 0.0005) despite an essentially equal number of female and male hospital admissions. There was a single statistically significant ECG correlate: a more vertical QRS axis in women (+14.1 degrees +/- 45.3 degrees vs. -5.6 degrees +/- 31.3 degrees; p = 0.034). The T waves were basically symmetric (68%), the influence of this factor usually altering the characteristically asymmetric T wave inversions of right bundle branch block (4 of 5) and left ventricular hypertrophy (21 of 36). Asymmetry was mainly associated with digoxin therapy (21 of 32 patients taking digoxin; p less than or equal to 0.0005) and a corrected QT (QTc) interval (0.433 +/- 0.095) shorter than with symmetric T wave inversions (0.507 +/- 0.074; p less than or equal to 0.0005) though not reaching the degree of shortening expected for digitalization. Twenty-eight patients admitted for acute myocardial infarction and 23 for a central nervous system disorder accounted for the majority of patients with symmetric T wave inversion. Fifteen of 18 patients who had coronary angiography had some degree of coronary artery disease: 3 had angiographically normal coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)