Objective: To explore the relationship among extracellular volume (ECV), native T1 and systolic strain in hypertrophic cardiomyopathy (HCM) and hypertensive patients with left ventricular hypertrophy (HTN LVH) with mild reduced or preserved ejection fraction. Methods:T1 mapping was performed in 45 Late gadolinium enhancement positive (LGE+) HCM subject (mean age, 53+6 years), 11 LGE negative (LGE-) HCM subject (mean age, 56+5 years) and 20 HTN LVH (mean age, 55+6 years) on a 3.0 T MR using modified look-locker inversion-recovery (MOLLI) pulse sequence. Mean T1 value, ECV and circumferential strain parameters were determined for each subject. Results: Overall, HCM subjects had higher native T1 value (1242.92+68.94 vs.) and ECV (0.31+0.05) compared with those of HTN LVH subjects (1197.00+46.80,0.27+0.04), (P<0.05). In the subgroup analysis, HCM LGE+ subjects had highest native T1 value among the three groups. HCM LGE+ subjects had higher ECV than LGE- subjects. HCM LGE- subjects had higher ECV than HTN LVH subjects (p<0.05).Peak systolic circumferential strain and early diastolic strain rates were reduced in HCM LGE+ subjects compared with HCM LGE- and HTN LVH subjects. (P<0.05). Reduced peak systolic and early diastolic circumferential strain rate were associated with increased levels of ECV and native T1value among all the subjects. Conclusion: HCM LGE+ subjects had longer native T1 and higher ECV, and associated reduction in early diastolic strain rate and peak systolic circumferential strain compared with HCM LGE- and HTN LVH patients with mild reduced or preserved ejection fraction.