The study sought to determine the duration of standing needed to detect most cases of orthostatic hypotension (OH) in the emergency room (ER) and to correlate OH with symptoms, hospitalization and survival. Patients attending a tertiary-center ER within a 2-month period underwent orthostatic tests after 1, 3 and 5 min of standing. OH was defined as a drop of > or = 20 mmHg in systolic pressure or > or = 10 mmHg in diastolic pressure on assuming an upright posture. Of the 814 patients tested (402 men, mean age 56.6 +/- 19.9 years), 206 (25.3%) had OH, detected in most cases (83.5%) after 3 min of standing. OH was associated with significantly higher supine systolic (p = 0.013) and diastolic (p = 0.004) blood pressure, symptoms of syncope (r = 0.11, p < 0.001) or dizziness (r = 0.14, p < 0.0001) and risk of hospitalization (50.9% vs 22.9%, p < 0.0001). Crude mortality was similar between patients with and without OH (13.8% vs 8.7%, p = 0.06). However, on age-adjusted analysis, patients older than 75 years with OH had significantly increased mortality (p = 0.04). In conclusion, 3 min of standing is apparently sufficient for the diagnosis of most cases of OH. Considering the high rate of OH and its predictive value for hospitalization, it should be routinely assessed in all ER patients.