Maximal elastance (E max : maximal ratio of pressure over volume) of left ventricular myocardium obtained from time-varing elastance curves represents myocardial contractility, which is independent of preload and afterload. A non-invasive method of quantifying myocardial global contractility using a single systolic PV loop was developed by Senzaki et al., and extended by Lee et al. by measuring time-volume curve using gated myocardial SPECT. Since these previous methods provide only the overall contractile function of left ventricle, we developed a method to quantify the regional contractility of myocardium. For total 55-72 regions, regional volume curve was estimated. Regional volume curves were obtained by extracting endocardial surface of left ventricle from each gated frame. Assuming the isopressure in left ventricular cavity, time-pressure curve obtained using tonometry was used for every region. We implemented software to estimate regional contractility with graphic user interface in Windows environment using VC++, in which gated myocardial SPECT is processed to acquire regional volume curve. The regional contractility developed in this study will be useful for the quantitative assessment of abnormality in regional mechanical function of myocardium in heart disease.