BACKGROUND The circadian pattern of blood pressure (BP) has yet to be defined among individuals with orthostatic hypotension (OH). The objective of this study was to evaluate whether OH is associated with nocturnal change in systolic BP. METHODS In a prospective study, we evaluated patients who were referred for 24-h ambulatory blood pressure monitoring (ABPM). All subjects underwent orthostatic BP testing before recording their respective 24-h ABPM. RESULTS The study includes 185 subjects, 114 males, mean age 58 ± 18 years (range 19-89). Participants were classified, based on pattern of systolic BP changes at night, as dippers (greater than 10% decrease; n = 74), nondippers (0-10% decrease; n = 77), and reverse-dippers (increase; n = 34). Nineteen patients (10.3%) had OH. Almost all participants with OH (95%) had an abnormal diurnal BP pattern, and most of them (58%) were reverse-dippers, whereas only 56% of the participants without OH had an abnormal diurnal BP variation, and only 14% were reverse-dippers (P < 0.001). Systolic BP decreased with upright posture by 12 and 2 mm Hg in the reverse-dippers and the nondippers, respectively, and increased by 2 mm Hg in the dippers (P < 0.001). Postural changes in systolic BP were inversely related to the changes between day and night BP readings(r = -0.43; P < 0.01). In a multivariate linear regression analysis, orthostatic BP change, use of ≥2 antihypertensive drugs and female sex were related to nocturnal BP changes. CONCLUSIONS The decrease in BP during upright posture may be a marker of nondipping or reverse-dipping pattern of diurnal BP.