© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY. Published by BMJ. INTRODUCTION: Recent evidence suggests that larger blood pressure reductions and multiple antihypertensive drugs may be harmful in older people, particularly frail individuals with polypharmacy and multimorbidity. However, there is a lack of evidence to support deprescribing of antihypertensives, which limits the practice of medication reduction in routine clinical care. The aim of this trial is to examine whether antihypertensive medication reduction is possible in older patients without significant changes in blood pressure control at follow-up.METHODS AND ANALYSIS: This trial will use a primary care-based, open-label, randomised controlled trial design. A total of 540 participants will be recruited, aged ≥80 years, with systolic blood pressure <150 mm Hg and receiving ≥2 antihypertensive medications. Participants will have no compelling indication for medication continuation and will be considered to potentially benefit from medication reduction due to existing polypharmacy, comorbidity and frailty. Following a baseline appointment, individuals will be randomised to a strategy of medication reduction (intervention) with optional self-monitoring or usual care (control). Those in the intervention group will have one antihypertensive medication stopped. The primary outcome will be to determine if a reduction in medication can achieve a proportion of participants with clinically safe blood pressure levels at 12-week follow-up (defined as a systolic blood pressure <150 mm Hg), which is non-inferior (within 10%) to that achieved by the usual care group. Qualitative interviews will be used to understand the barriers and facilitators to medication reduction. The study will use economic modelling to predict the long-term effects of any observed changes in blood pressure and quality of life.ETHICS AND DISSEMINATION: The protocol, informed consent form, participant information sheet and all other participant facing material have been approved by the Research Ethics Committee (South Central-Oxford A; ref 16/SC/0628), Medicines and Healthcare products Regulatory Agency (ref 21584/0371/001-0001), host institution(s) and Health Research Authority. All research outputs will be published in peer-reviewed journals and presented at national and international conferences.TRIAL REGISTRATION NUMBER: EudraCT 2016-004236-38; ISRCTN97503221; Pre-results.