Myocardial T2 mapping has emerged as a promising tool for edema characterization and detection of myocardial inflammation. T2 mapping is conventionally performed under breath-hold by acquiring multiple T2-prepared images using 2D bSSFP. However, 2D imaging and breath-holding impedes high spatial resolution, limits whole-heart coverage and can be challenging in some patients. We developed a free-breathing 3D whole-heart T2 mapping framework that achieves high isotropic resolution in a clinically feasible scan time in healthy subjects. Here we sought to quantify the reproducibility and repeatability of this technique and assess its performance to detect myocardial inflammation in a clinical setting.