To evaluate the relationship between the adiponectin levels and left ventricular mass index (LVMI) in uncomplicated obese subjects. Fifty-nine subjects were assigned to the obese (BMI >= 30 kg/ml) and 58 to the lean (BMI<30 kg/m(2)) group. Plasma glucose, insulin, serum total cholesterol and high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, triglycerides and adiponectin were measured. Insulin resistance was determined by the Homeostasis Assessment Model (HOMA-IR). The left ventricular functions of all subjects were determined by 2D and pulse wave Doppler echocardiography. LVMI was calculated as left ventricular mass (LVM) normalized for height in M-2.7. The obese group displayed significantly higher LVMI and late mitral inflow velocity. Thirty-three obese subjects met the criteria for left ventricular hypertrophy (LVH) and had lower serum adiponectin levels compared with obese subjects without LVH and lean subjects (p<0.05). Adiponectin was negatively correlated with LVMI (R: -0.277, p: 0.002). Furthermore, during the partial correlation analysis where HOMA-IR was controlled, the negative correlation between adiponectin and LVMI progressed (r: -0.283, p: 0.002). The linear regression analysis showed an independent relationship between LVMI and adiponectin. (beta: -0.214, p: 0.01) Obesity is associated with LVH. This study showed direct influence of adiponectin on LVMI.