Purpose: Geriatric rehabilitation inpatients who suffer from acute and chronic diseases that aggravate blood pressure (BP) dysregulation, may be particularly susceptible to orthostatic hypotension (OH). OH may increase the risk of cerebral small vessel disease and subsequent white matter hyperintensities inducing cognitive impairment (CI). This study investigates the association between OH and cognition in geriatric rehabilitation inpatients. Materials and methods: Geriatric rehabilitation inpatients of the observational, longitudinal REStORing health of acutely unwell adulTs (RESORT) cohort in Melbourne, Australia, underwent intermittent BP measurements during active standing or partial postural change to sitting (when unable to stand). OH was defined as a systolic BP drop ≥20 mmHg and/or diastolic BP drop ≥10 mmHg within three minutes after postural change. CI included dementia diagnosis, Mini-Mental State Examination (MMSE) score <24 points (categorized as 18-23 (mild CI) and <18 points (severe CI)), Montreal Cognitive Assessment score <26 points or Rowland Universal Dementia Assessment Scale score <23 points. Results: In geriatric rehabilitation inpatients (n=1232, mean age 82.3 years (SD 8.2), 57.5% female), OH, CI and dementia prevalence was 20.0%, 61.0% and 20.4% respectively. MMSE was scored 18-23 in 32.6% and <18 points in 27.8% of patients (n=1033). In standing patients (51.7%), OH was associated with CI (p=0.045) and dementia (p=0.021), with a trend for MMSE scores <18 points (p=0.080), but not for MMSE scores 18-23 points (p=0.528). No association was found between seated OH and cognition. Conclusion: OH assessed by active standing using intermittent BP measurements was associated with worse cognition in geriatric rehabilitation inpatients.