30 patients with delayed contrast enhancement in patterns suggestive of myocardial infarctions were reviewed. Infarct mass was quantitatively measured using short axis images obtained in the delayed phase of gadopentetate administration. Left ventricular mass and ejection fraction were measured using short axis, steady state free precession images. A relationship is drawn between increased mass of infarction and decreased left ventricular ejection fraction. For each gram of infarct, there is a 0.5 % reduction in ejection fraction (EF = 50 - (0.48 x gm infarcted myocardium); r²= 0.49). For each % increase of infarcted myocardium, there is a 0.67 % reduction in ejection fraction (EF = 50 - (0.67 x percent of infarcted myocardium); r²= 0.39). Left ventricular ejection fraction correlates inversely with the mass of myocardium with delayed enhancement on cardiac MRI.