Orthostatic hypotension is a common condition seen in up to one-third of community-dwelling and two-thirds of hospitalized older people. It is part of a spectrum of abnormal cardiovascular responses to postural challenge and is associated with syncope, dizziness, falls, volume depletion, drug side-effects and an increased mortality. This article discusses the current classification of orthostatic hypotension and related conditions, and the clinical importance of the control of the cardiovascular response to orthostasis. These are considered with particular reference to the measurement of postural cardiovascular responses in the routine clinical setting. By improving understanding of the methods that are used for assessment of postural changes in blood pressure, clinicians should have greater confidence in the reliability of measurement and in their interpretation.