The objective of this study is to establish the efficacy of adherence therapy (AT) compared with treatment as usual (TAU) in reducing blood pressure (BP) in non-compliant hypertensive patients. This study was designed as a parallel-group single-blind randomised controlled trial. The study was carried out at three general hospital outpatient clinics in Jordan. A total of 136 non-compliant hypertensive patients with a mean baseline BP of 164.5 mm Hg (s.d. 10.0) over 102.2 mm Hg (s.d. 7.0) participated in the study. 7 weekly 20-min sessions of AT in addition to TAU. The main outcome of this study is systolic blood pressure (SBP) at 11-weeks follow-up. In all, 68 patients received TAU and 68 AT. Intention-to-treat analysis included all participants randomised. AT lowered SBP by -23.11 mm Hg (95% CI: -25.85, -20.36) and diastolic BP (DBP) by -15.18 mm Hg (95% CI: -17.55, -12.80) at 11 weeks compared with TAU. Adherence (measured by pill counting) was also improved in the AT group by 37% at 11 weeks compared with TAU. No significant adverse events were reported. AT increases adherence to medication for hypertension which then leads to a clinically important reduction in BP.Journal of Human Hypertension advance online publication, 17 February 2011; doi:10.1038/jhh.2010.133.