Background Uncontrolled blood pressure ( BP) is commonly observed in patients receiving antihypertensive agents. However, its relationship with early left ventricular ( LV) dysfunction has not been elucidated. Methods This study enrolled 276 patients with treated hypertension and 85 healthy controls. The 140/90 mm Hg was used to define controlled ( HT1 group, n=145) or uncontrolled BP ( HT2 group, n=131) according to the concurrent guidelines. LV myocardial function was assessed by two-dimensional speckle tracking imaging, and the circumferential end-systolic wall stress ( cESS)-corrected mid-wall fraction shortening ( MWFS), systolic longitudinal (εLs-18), circumferential (εCs-18), and radial (εRs-18) strain were measured. Results Despite similar ejection fraction, the HT1 and HT2 groups displayed an overall reduction in the cESS-corrected MWFS (13.4±2.7 vs 11.7±1.7 vs 15.5±1.2), εLs-18 (15.6±2.8 vs 13.0±2.2 vs 17.4±2.8), εCs-18 (17.3±3.4 vs 14.1±2.7 vs 18.9±3.3), and εRs-18 (18.4±4.0 vs 14.8±3.1 vs 20.5±4.5) %·cm2/kdyne·10−2 when compared with the control group (all P<.001). The changes were more obvious in the HT2 group, regardless of LV hypertrophy. Reductions in the cESS-corrected MWFS and εLs-18 were seen in 68 (25%) and 52 (19%) patients, respectively. Uncontrolled BP were 4.365 times (95% CI 2.203-8.648, P<.001) and 3.928 times (1.851-8.337, P<.001) more likely to be associated with the changes. Conclusions Uncontrolled BP in hypertensive patients is associated with further reduction in LV myocardial function detected by advanced echocardiographic techniques, which cannot be explained by the increase in afterload. It might be regarded as a composite risk factor for earlier and faster development of clinical heart failure, therefore, a simplified treatment target.