Fifty consecutive patients having had cardiac catheterisation for coronary artery disease also underwent testing by three non-invasive methods commonly employed for assessment of left ventricular function. These included the first pass radionuclide ejection fraction, fractional shortening of the M-mode echocardiographic left ventricular internal dimension, and pre-ejection period/left ventricular ejection time ratio derived from systolic time intervals (PEP/LVET). Linear correlations of these non-invasive measures with cineangiographic ejection fractions were calculated. The first pass radionuclide ejection fraction correlated best. Echocardiograms and systolic time intervals proved less versatile since 11 of 50 echocardiograms were technically not suitable for measurement and 11 of 50 systolic time intervals could not be used because of left ventricular conduction delays. Overall, radionuclide ventriculography proved to be the most accurate and practical of these non-invasive techniques in evaluating left ventricular function in this group of patients with coronary artery disease.