OBJECTIVE This study was designed to determine if fractional systolic/diastolic pressures act as predictors of the extent of coronary artery disease. METHODS A total of 545 consecutive patients (305 men, 240 women, with mean age 54.2 years) were involved in the study. The patients were diagnosed with coronary and non-coronary artery disease confirmed by angiography. RESULTS 353 patients were confirmed to have coronary artery disease, with 134 cases involving one vessel, 101 two vessels and 118 three vessels. There were significant differences between brachial and ascending aortic systolic blood pressures, fractional systolic blood pressures and fractional diastolic blood pressures in the patients with coronary artery disease compared with patients with non-coronary artery disease. Blood pressure measured in the brachial artery was higher than the pressure measured in the ascending artery. Ascending aortic fractional systolic/diastolic pressures were associated with coronary Gensini score, and were significantly related to the number of diseased vessels. CONCLUSIONS Fractional systolic and diastolic pressures in the ascending aorta were strong predictive factors for the extent of coronary artery disease. Central pressures measured invasively in the ascending aorta were more predictive than peripheral pressures for the evaluation of coronary artery disease.