To compare the measurement of global left-ventricular (LV) function parameters of 64-slice multidetector-row computed tomography (MDCT) between 20- and 10-reconstruction phases. Fifty five patients with suspected or known coronary artery disease underwent 64-slice MDCT. LV end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were measured from MDCT data sets using threshold-based volume segmentation and reconstruction at every 5% (20 phases) and 10% (10 phases) step through the R-R interval. These global functional parameters were compared to those obtained via two-dimensional transthoracic echocardiography (2D-TTE), considering the reference standard. The required time for CT data analysis was checked. Agreement for parameters of LV global function was determined using Pearson’s correlation coefficient (r) and Bland–Altman analysis. LV volumes (EDV−5% 87.5 ± 17.1 ml, EDV−10% 87.7 ± 16.3 ml; ESV−5% 32.4 ± 10.6 ml, ESV−10% 31.9 ± 9.9 ml; SV−5% 55.1 ± 10.5 ml, SV−10% 55.8 ± 9.9 ml; mean ± SD) and EF (EF−5% 63.4 ± 6.2%, EF−10% 63.9 ± 5.8%) did not differ significantly between the 20- and 10 phase reconstructions, and evidenced good to excellent correlation (r = 0.786–0.896, all P < 0.001) with the 2D-TTE results. The mean required time for CT data analysis in the 20- and 10 phase reconstructions were 15.5 ± 4.0 and 7.3 ± 2.5 min. Within MDCT, using 10-phase image reconstruction is sufficient to evaluate LV volumes and EF, and is also more time-effective than 20-phase reconstruction.