Our objective was to study the effect of hydroalcoholic extract of M. oleifera seeds on high blood pressure in Wistar rat. After 21 days of a high sodium diet, the value of systolic blood pressure and diastolic blood pressure increased from 87. 2 ± 1.96 / 58 ± 0.89 mm to 200.8 ± 0.49 /151.2 ± 1.2 mm Hg (p < 0.05). Administered orally, the extract reduces the high blood pressure of hypertensive rats. It returns to its normal value after 19 days for the control batch, versus 9, 6, and 3 days for the animals treated with the extract at doses 100, 200, and 400 mg/kg (P < 0.05). The extract also has a diuretic activity; the 24 h urinary volume increases from 4.8 ± 0.14 ml in control group, versus 6.85 ± 0.1, 8.3 ± 0.13 and 10.7 ± 0.5 ml in groups treated with the extract at doses 100, 200 and 400 mg/kg (p < 0.05), while natriuresis increases from 2.06 ± 0.05 mEq/L in control group, versus 2.92 ± 0.05; 6.82 ± 0.11 and 10.73 ± 0.17 mEq/L in animals treated with the extract at doses 100, 200 and 400 mg/kg (p < 0.05). In vitro, it relaxes the isolated aorta contracted with norepinephrine at the concentration of 10-5 M in the bath, with EC50 equal to 2.06 mg/ml (p < 0.05). These results show that the hydroalcoholic extract of M. oleifera seeds has antihypertensive activity through its diuretic and vasodilator effects.