The aims of this study are to investigate the frequency of garlic usage in hypertensive population and to evaluate acute effect of garlic and garlic tablets on blood pressure in patients with hypertension. 4102 of the 7703 patients (53.3%) reported that they were using garlic. No significant effect on blood pressure was observed in any of the three groups (placebo, garlic or garlic tablets). Use of garlic is common among the hypertensive population, garlic and garlic tablets do not have acute blood pressure lowering effect, and a special education program informing patients and public about garlic is required.