BACKGROUND: Although cupping remains a popular treatment modality worldwide, its efficacy for most diseases, including hypertension, has not been scientifical y evaluated. OBJECTIVE: We aimed to determine the efficacy of wet-cupping for high blood pressure, and the incidence of the procedure’s side effects in the intervention group. DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS: This is a randomized control ed trial conducted in the General Practice Department at King Abdulaziz University Hospital, Jeddah, Saudi Arabia, between May 2013 and February 2014. There were two groups (40 participants each):intervention group undergoing wet-cupping (hijama) in addition to conventional hypertension treatment, and a control group undergoing only conventional hypertension treatment. Three wet-cupping sessions were performed every other day. MAIN OUTCOME MEASURE: The mean systolic and diastolic blood pressures were measured using a validated automatic sphygmomanometer. The fol ow-up period was 8 weeks. RESULTS: Wet-cupping provided an immediate reduction of systolic blood pressure. After 4 weeks of fol ow-up, the mean systolic blood pressure in the intervention group was 8.4 mmHg less than in the control group (P = 0.046). After 8 weeks, there were no significant differences in blood pressures between the intervention and control groups. In this study, wet-cupping did not result in any serious side effects. CONCLUSION: Wet-cupping therapy is effective for reducing systolic blood pressure in hypertensive patients for up to 4 weeks, without serious side effects. Wet-cupping should be considered as a complementary hypertension treatment, and further studies are needed. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01987583.