There are no epidemiological studies of orthostatic hypotension (OH)/hypertension (OHT) and orthostatic dizziness (OD) in adults across all age groups. The aim of this study is to examine the prevalence and correlates of OH, OHT, and OD in community dwellers aged > or = 20 years. OH was defined as a decline in systolic/ diastolic blood pressure of > or = 20/10 mmHg when a person stood up from a supine position. OHT was a postural increase of > or = 20 mmHg in systolic blood pressure. OD was dizziness, lightheadedness, or faintness as the person stood up. A total of 1,638 adults were included. Subjects were classified as normotensive, pre-hypertensive, or hypertensive. The prevalences of OH, OHT, and OD were 15.9, 1.1, and 4.8%, respectively. OD was associated with neither OH nor OHT. None of the subjects aged < 40 had OHT; hypertension (p = 0.030) and female gender (p < 0.001) were the independent correlates of OH and OD, respectively, in that age range. For subjects aged > or = 40 years, age (p = 0.003), pre-hypertension (p = 0.024), hypertension (p = 0.008), and diabetes mellitus (p = 0.036) were independently related to OH. Age (p < 0.001) and supine systolic blood pressure (p = 0.023) were the correlates of OHT. Female gender (p < 0.001) and sedatives/hypnotics (p = 0.040) were associated with OD. In conclusion, age, pre-hypertension, hypertension, and diabetes mellitus were important determinants of OH. OD was more prevalent in women and in subjects using sedatives/hypnotics. The risk of OHT increased with age and with supine systolic blood pressure in adults aged > or = 40 years. OH and OHT cannot be determined solely from the presence of OD because of their dissociation.