Purpose: The aim of this study is to investigate the reproducibility of the quantitative assessment of segmental wall motion and systolic thickening provided by an automatic quantitation algorithm. Materials and Methods: Tc-99m-MIBI gated myocardial SPECT with dipyridamole stress was performed in 31 patients with known or suspected coronary artery disease (4 with single, 6 with two, 11 with triple vessel disease; ejection fraction $51{pm}14%$) twice consecutively in the same position. Myocardium was divided into 20 segments. Segmental wall motion and systolic thickening were calculated and expressed in mm and % increase respectively, using $AutoQUANT^{TM}$ software. The reproducibility of this quantitative measurement of wall motion and thickening was tested. Results: Correlations between repeated measurements on consecutive gated SPECT were excellent for wall motion (r=0.95) and systolic thickening (r=0.88). On Bland-Altman analysis, two standard deviation was 2 mm for repeated measurement of segmental wall motion, and 20% for that of systolic thickening. The weighted kappa values of repeated measurements were 0.807 for wall motion and 0.708 for systolic thickening. Sex, perfusion, or segmental location had no influence on reproducibility. Conclusion: Segmental wall motion and systolic thickening quantified using $AutoeUANT^{TM}$ software on gated myocardial SPECT offers good reproducibility and is significantly different when the change is more than 2 mm for wall motion and more than 20% for systolic thickening.