Orthostatic hypotension (OH) is a common clinical problem that affects 6–30% of community-dwelling older adults, and this rate rises to 60% for inpatients. OH, is associated with mortality, ischemic stroke, falls, cognitive failure, impaired sleep quality, depression, renal failure, and cognitive impairment in older adults. Therefore, evaluation of OH should necessarily be a part of the comprehensive geriatric assessment. According to the consensus statement (CS) on the definition of OH published in 2011, the diagnosis of OH is made in the event of at least 20 mmHg sustained reduction of systolic blood pressure (SBP) and/or at least 10 mmHg sustained reduction of diastolic blood pressure (DBP) within the first 3 min of standing or head-up tilt to at least 60° on a tilt table. In patients with supine hypertension, a sustained reduction in SBP of 30 mmHg may be a more appropriate criterion. Initial and delayed OH are variants of OH. Although there is a consensus report for the diagnosis of OH, discussions about the diagnostic criteria and optimal method continue in the current literature. CS definition on OH is appropriate for screening and standardization in clinical studies, but it should be kept in mind that it may be inadequate for the diagnosis of OH in older adults in clinical practice. OH, is often classified as neurogenic and non-neurogenic. Another form of classification is acute and chronic OH. Remarkably, the causes of non-neurogenic and acute OH, as well as neurogenic and chronic OH, generally overlap.