Background: Men and women differ in the risk of cardiovascular disease, but the underlying mechanisms are not completely understood. We examined possible sex-related differences in supine and upright cardiovascular regulation. Methods: Hemodynamics were recorded from 167 men and 167 women of matching age (∼45 years) and body mass index (∼26.5 kg/m2) during passive head-up tilt. None had diabetes, cardiovascular disease other than hypertension, or antihypertensive medication. Whole-body impedance cardiography, tonometric radial blood pressure, and heart rate variability were analyzed. Results were adjusted for height, smoking, alcohol intake, mean arterial pressure, plasma lipids and glucose. Results: Supine hemodynamic differences were minor: lower heart rate (−4%) and higher stroke volume (+7.5%) in men than women (p55 years). Heart rate variability analyses showed higher low frequency to high frequency ratio in supine (p