Gated myocardial perfusion SPECT (GSPECT) is a major clinical tool, widely used for performing myocardial perfusion imaging procedures. In this review, we have presented the fundamentals of GSPECT and the ways in which the functional measurements it provides have contributed to the emergence of myocardial perfusion SPECT in its important role as a major tool of modern cardiac imaging. GSPECT imaging has shown unique capability to provide accurate, reproducible and operator-independent quantitative data regarding myocardial perfusion, global and regional systolic and diastolic function, stress-induced regional wall-motion abnormalities, ancillary markers of severe and extensive disease, left ventricular geometry and mass, as well as the presence and extent of myocardial scar and viability. Adding functional data to perfusion provides an effective means of increasing both diagnostic accuracy and reader's confidence in the interpretation of the results of perfusion scans. Assessment of global and regional LV function has improved the prognostic power of myocardial perfusion SPECT and has been shown in a large registry to add to the perfusion assessment in predicting benefit from revascularization.