Hypertension-related deaths amount to 9.4 million deaths each year. Despite existing medications for treatment, medication non-adherence serves as a barrier to effective treatment. With the rapid adoption of smartphone technologies, previous studies have examined the impact on hypertension of a smartphone application, but the impact of a stand-alone smartphone application on blood pressure had not been tested in a rigorous manner with regards to hypertension control. The Medication Adherence Improvement Support App For Engagement—Blood Pressure (MediSAFE-BP) study randomized 411 patients with poorly-controlled hypertension to the Medisafe smartphone app or control and found that the app resulted in small but significant improvements in medication adherence but did not impact blood pressure control.