Background: Little is known about the impact of hospitalization on antihypertensive pharmacotherapy and blood pressure control in older persons. Objectives: The aim of this study was to explore the impact of hospitalization on the management of hypertension and antihypertensive pharmacotherapy in a cohort of older patients with a documented diagnosis of hypertension. Methods: A retrospective, cross-sectional medical record audit was conducted in a large Australian metropolitan teaching hospital. Patients aged 65 years or older, admitted between January 1st 2010 and December 31st 2010, and with a documented diagnosis of hypertension in their medical record were included in the study. Antihypertensive pharmacotherapy and blood pressure control was compared between admission and discharge. Factors associated with changes to antihypertensive pharmacotherapy were identified. Results: Changes to antihypertensive pharmacotherapy occurred in 39.5 % (n = 135) of patients (n = 342). On discharge, the proportion of patients receiving antihypertensive pharmacotherapy (89.0 vs 85.3 %, p < 0.0001) and the mean number of antihypertensive agents per patient (1.7 ± 1.1 vs 1.5 ± 1.1, p < 0.0001) declined compared with admission. Adverse drug reactions [odds ratio (OR) = 5, 95 % confidence interval (CI): 2.80–9.34] were the main reason documented for antihypertensive pharmacotherapy changes. Patients admitted under the care of medical (OR = 0.3, 95 % CI: 0.17–0.70) or surgical (OR = 0.3, 95 % CI: 0.12–0.53) specialties were less likely to experience changes to their antihypertensive pharmacotherapy than those treated by gerontology or cardiology teams. Conclusions: Hospitalization has a significant impact on antihypertensive pharmacotherapy. Two out of every five older persons on antihypertensive medications will experience changes to their regimens during admission to hospital with most changes in antihypertensive pharmacotherapy due to adverse drug reactions.