Experiments were performed on male and female spontaneously hypertensive rats weighing 310-340 g (10 animals per group). The oral administration of 200 mg/kg/day of saponins from Herniaria glabra for 30 days, resulted in a significant decrease in blood pressure in hypertensive rats. The systolic and diastolic blood pressure decreased significantly and respectively from 187.60 +/- 20.63/119.00 +/- 7.09 mmHg at day 0 (D0) to 141.60 +/- 7.51/90.40 +/- 7.68 mmHg at day 30 (D30), p < 0.001 (vs. 186.30 +/- 11.27/114.10 +/- 12.00 mm Hg at D0 to 154.50 +/- 6.38/132.3 +/- 7.68 mmHg at D30 in furosemide-treated group, p < 0.001). Control animals receiving placebo did not show any significant variation in the mean arterial pressure. The effect of saponins of Herniaria glabra on renal function was evaluated in spontaneously hypertensive rats using clearance techniques. Glomerular filtration rate was constant in the control rats and increased significantly in the hypertensive rats after saponins treatment (5.55 +/- 0.32 vs. 6.03 +/- 0.43 ml.min-1.kg-1 in the control (C) and saponins (S) groups, respectively, p < 0.05). Saponins administration provoked an increase in urinary flow (59.38 +/- 5.85 ml.kg-1.24 h-1 vs. 36.92 +/- 5.17 ml.kg-1.24 h-1, p < 0.001). Saponins also increased potassium excretion (6.89 +/- 0.81 mmol.kg-1.24 h-1 vs. 5.40 +/- 0.51 mmol.kg-1.24 h-1, p < 0.001) and sodium excretion (10.74 +/- 1.21 mmol.kg-1.24 h-1 vs. 7.25 +/- 0.54 mmol.kg-1.24 h-1, p < 0.001) as well as chloride excretion (13.59 +/- 1.04 mmol. kg-1.24 h-1 vs. 9.67 +/- 0.77 mmol.kg-1.24 h-1, p < 0.001). It is concluded that chronic oral administration of saponins from Herniaria glabra decreased the arterial blood pressure and affected salt and water transport in renal tubules.