Objective:To study left ventricular function and morphology in non-hypertensive obese females and to relate the findings to body mass index (BMI) and to an index of body fat distribution (waist: hip ratio).Design:Cross-sectional study.Setting:Obesity unit in city hospital.Subjects:Healthy obese females (n = 22) with BMI >25 and <40 kg/m2and a non-obese, age-matched control group (n = 20) with BMI <25 kg/m2.Main outcome measures:Blood pressure and non-invasive indices of left ventricular morphology and diastolic and systolic function.Results:The obese group had significantly higher blood pressure, larger left ventricular end-diastolic diameter, greater left ventricular mass; larger left atrial size, signs of decreased left ventricular distensibility and prolonged left ventricular relaxation time index, and signs of supernormal systolic left ventricular function (as judged from the relationship between fractional shortening and end-systolic wall stress) than the non-obese controls. The results also indicated that left ventricular wall thickness and mass were well adapted to the increase in afterload, as judged by analyses of end-systolic wall tension and end-systolic wall stress.Conclusion:In confirmation of several previous studies, obesity was closely associated with an increase in blood pressure and left ventricular mass, and with early signs of disturbed left ventricular diastolic function. Left ventricular wall thickness and mass were well adapted to the increase in afterload; thus, we could not identify any non-afterload-dependent effect of an increase in BMI or waist: hip ratio on left ventricular hypertrophy.