Objectives: To critically evaluate the effectiveness of yoga as a treatment of hypertension. Methods: Seventeen databases were searched from their inceptions to January 2014. Randomized clinical trials (RCTs) were included, if they evaluated yoga against any type of control in patients with any form of arterial hypertension. Risk of bias was estimated using the Cochrane criteria. Three independent reviewers performed the selection of studies, data extraction, and quality assessments. Results: Seventeen trials met the inclusion criteria. Only two RCTs were of acceptable methodological quality. Eleven RCTs suggested that yoga leads to a significantly greater reduction in systolic blood pressure (SBP) compared to various forms of pharmacotherapy, breath awareness or reading, health education, no treatment (NT), or usual care (UC). Eight RCTs suggested that yoga leads to a significantly greater reduction in diastolic blood pressure (DBP) or night-time DBP compared to pharmacotherapy, NT, or UC. Five RCTs indicated that yoga had no effect on SBP compared to dietary modification (DIM), enhanced UC, passive relaxation (PR), or physical exercises (PE). Eight RCTs indicated that yoga had no effect on DBP compared to DIM, enhanced UC, pharmacotherapy, NT, PE, PR, or breath awareness or reading. One RCT did not report between-group comparisons. Conclusion: The evidence for the effectiveness of yoga as a treatment of hypertension is encouraging but inconclusive. Further, more rigorous trials seem warranted. Keywords: Complementary and alternative medicine; Effectiveness; Hypertension; Systematic review; Yoga.