Objective To investigate the possible roles of hemodynamics, circulating hormones, cell cation transport and cyclic nucleotides in left ventricular hypertrophy (LVH) of essential hypertension (EH) in vivo. Methods Blood pressure, total peripheral resistance (TPR) and plasma norepinephrine (NE), endothelin (ET), angiotensin Ⅱ (AngⅡ), endogenous digitalis like substances (EDLS) and atrial natriuretic peptide (ANP) were determined, along with the measurements of lymphocytic membrane ion pumps, cations and cyclic nucleotides in 45 EH patients with LVH (12 concentric hypertrophy, 33 eccentric hypertrophy), 30 normal subjects and 45 EH patients without LVH (as double concurrent controls). Multiple stepwise regression analysis was computed using left ventricular mass index (LVMI) as dependent variable and 22 parameters as independent variables. Results (1) In EH patients with LVH, increases were seen in systolic blood pressure, mean arterial pressure (MAP) and NE, ET, AngⅡ, EDLS and ANP as well as lymphocytic Na +, Ca 2+ , cAMP and cAMP/cGMP ratio, while Na + K + ATPase and Ca 2+ ATPase activities, K + and Mg 2+ decreased. (2) Five hormones were related respectively to ion pumps, Na +, Ca 2+ and cyclic nucleotides. (3) LVMI were correlated with NE, ET, AngⅡ and EDLS, Ca 2+ ATPase, Na +, cAMP and cAMP/cGMP ratio. (4) The regression equation revealed that NE, ET, Ca 2+ ATPase, Mg 2+ and cAMP were the independent factors affecting LVH. (5) TPR and AngⅡ were higher, K + was lower in concentric LVH than those in eccentric LVH. Conclusion The changes of hemodynamics, circulating hormones, cell cation transport and cyclic nucleotides, or their interaction may be involved in the pathogenesis of LVH in EH. NE, ET. Ca 2+ ATPase, Mg 2+ and cAMP seem to play more important parts in LVH . TPR , whereas AngⅡ and K + may relate to cocentric LVH.