Myocardial perfusion imaging with single-photon emission computed tomography (SPECT) is important for the management of patients with suspected or known coronary artery disease. Stress myocardial perfusion images may be interpreted by visual inspection or by quantitative analysis. The use of visual inspection alone may introduce considerable observer variability and clinical usefulness of myocardial perfusion imaging may not be consistently reproduced in many laboratories using visual analysis. Relative myocardial distribution of imaging agents on SPECT images can be quantified and compared with normal data files by computer processing. Quantification of myocardial perfusion images provides a reproducible measure of the extent of perfusion abnormalities and defect reversibility. The quantification of myocardial perfusion images improves not only the overall diagnostic yield but also enhances reliability, accuracy, confidence, and reproducibility of interpretation. This review illustrates the current status and the future perspectives of myocardial perfusion quantification by SPECT imaging.