Postural stress tests are useful in the assessment of cardiovascular reflex response of normal subjects who may be involved in specialised occupations such as flying; in order to study the effects of physiological stresses such as heat stress, hypoxia, simulation of weightlessness; physiological evaluation of cosmonaut candidates, in patients who may have autonomic neuropathy. Most commonly quiet standing is used but head-up tilt table test and the application of lower body suction may provide a better method of evaluation. These three tests for assessing reflex cardiovascular function are discussed.