Good T1 estimation accuracy and precision is important for clinical application of the myocardial T1 mapping technique. Although the widely used T1 mapping technique, modified Look-Locker inversion-recovery (MOLLI), has good precision and reproducibility, it is not accurate. Several T1 estimation algorithms have been proposed to improve the accuracy for MOLLI. These algorithms however, often have reduced T1 estimation precision. We developed an improved MOLLI technique to achieve better accuracy and precision than the standard MOLLI sequence. Based on phantom and volunteer studies, a higher flip angle MOLLI with Bloch equation simulation and slice profile correction (BLESSPC) is used for T1 estimation.