Pathophysiological studies of tilt table aided orthostatic stress on humans were fifty years old before the evolution of head-upright tilt table testing into the diagnostic test of choice in vasovagal syncope. Variations in orthostatic tolerance demonstrated by tilt table testing were observed in normal subjects1,2 and in association with pregnancy,3 anxiety,4 prolonged inactivity5,6 and immersion.7 Tilt table testing was also used in the assessment of physiologic responses to orthostatic stress,8,9 weightlessness10 and parachuting11 by workers in aerospace and aviation medicine. Throughout these investigations, prolonged orthostasis was noted to provoke syncope in subgroups of those studied and subsequently the tilt table was used to investigate several components of the vasovagal response, notably cardiac output,12,13 changes in forearm blood flow14 and venous tone.15 Several authors commented on the occurrence of syncope in varying proportions of the subjects studied,1,3,8,11,15 while others commented on an increase in the frequency of syncope during tilting in those with a history suggestive of the vasovagal syndrome.11,16 It was not until 1986, however that the intellectual leap from interesting clinical observation to diagnostic utility was made, with the publication of the Westminster group’s landmark study on the usefulness of head-up tilt in the diagnosis of unexplained syncope.17 In this series,17 67% of patients with otherwise unexplained syncope developed syncopal symptoms associated with hypotension and bradycardia during prolonged head-up tilt. Only 10% of asymptomatic controls had similar reactions. The head-up tilt table test has since withstood extensive clinical and experimental scrutiny, and is currently the instrument of choice in the diagnosis of vasovagal syncope.18–21