Background Compared with the conventional Thrombolysis In Myocardial Infarction (TIMI) flow grade system, the corrected TIMI frame count (CTFC) quantifies coronary blood flow in a more reproducible fashion. The purpose of this study was to determine if the CTFC is affected by sex, body size, hemodynamics, or other selected clinical variables. Methods and Results CTFC was measured in 534 coronary arteries from 200 consecutive patients referred for coronary angiography. CTFC in each artery was related to patient variables (sex, age, race, and body surface area), clinical variables (cardiac rhythm, medication use, diabetes, hypertension, hypercholesterolemia, smoking, and left ventricular hypertrophy), angiographic variables (wall motion abnormality in each coronary artery distribution, left ventricular ejection fraction, percent stenosis in the artery, and presence of collaterals), and hemodynamic variables (aortic systolic and diastolic blood pressure and left ventricular end-diastolic pressure). By multivariate analysis, CTFC in all arteries was significantly associated with aortic systolic and diastolic pressures and body surface area. In addition, there were significant associations between CTFC and age and sex in some but not all arteries. Although significant, the absolute change in CTFC associated with these variables was small. Conclusions CTFC provides a quantitative assessment of coronary blood flow that varies only a small amount in association with body size, systemic arterial pressure, age, and sex. (Am Heart J 2000;140:308-14.)