Vasovagal syncope is the most common cause of transient loss of consciousness and recurrent vasovagal fainting has profound impact on quality of life. Physical counter maneuvers are applied as a means of tertiary prevention, but have so far only proven useful at the onset of a faint. This placebo-controlled cross over study tested the hypothesis that leg crossing increases orthostatic tolerance. Nine naive healthy subjects (6 females, median age 25 years (range 20-41), mean body mass index 23 (SD 2)) were subjected to passive head-up tilt combined with a graded lower body negative pressure challenge (20, 40, 60 mmHg) determining orthostatic tolerance thrice, in randomized order: a) control, b) with leg crossing and c) with oral placebo. Blood pressure (Finometer), heart rate, and changes in thoracic blood volume (impedance), stroke volume and cardiac output (Modelflow) were followed during orthostatic stress. Primary outcome was time to pre-syncope (systolic blood pressure 85mmHg, heart rate 140 bpm). With leg crossing, orthostatic tolerance increased from 26±2 to 34±2 min (placebo 23±3 min, p<.001). During leg crossing mean arterial pressure (81 versus 81 mmHg) and cardiac output (95 versus 94 % supine) remained unchanged, heart rate increase was lower (13 versus 18 bpm, p<.05), stroke volume higher (79 versus 74 % supine, p<.05) and there was a trend for lower thoracic impedance. Leg crossing increases orthostatic tolerance in healthy human subjects. As a measure of prevention it is a worthwhile addition to the management of vasovagal syncope.