The aim of this study was to explore the role of circulating endothelial progenitor cells (EPCs) and endothelial apoptotic microparticles in hypertensive patients with and without electrocardiographic left ventricular hypertrophy (LVH). Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC level by quantification of circulating EPC markers (defined as CD34(+)CD133(+), CD34(+)KDR(+)) and endothelial apoptotic microparticles (defined as CD31(+)/annexin V(+)) in peripheral blood samples. The LVH was defined by ECG with the Cornell voltage criteria. In total, 128 hypertensive patients (83 men and 45 women, aged 59±14 years) were enrolled in this study, in which 107 patients (84%) showed no electrocardiographic evidence of LVH, and 21 patients (16%) fulfilled the LVH criteria by ECG. There were no significant differences in basic characteristics between the two groups, but hypertensive patients with LVH had a higher urine albumin excretion rate than those without LVH (P=0.027). Furthermore, hypertensive patients with LVH were shown to have decreased circulating EPC numbers (all P<0.05) and adhesive function compared with those without LVH (LVH vs. no LVH: 14±6 vs. 30±6 cells per high-power field, P<0.001). Increased numbers of endothelial apoptotic microparticles were noted in hypertensive patients with LVH (4.2±4.9 vs. 2.4±3.4%, P=0.115), although the difference was not significant. This study showed that essential hypertensive patients with electrocardiographic LVH evidence have decreased circulating EPC numbers and adhesive function compared with those without LVH. These findings may explain the pathogenetic processes that link hypertensive LVH and endothelial injury in cardiovascular disease.