SummaryThe authors localize the effect of the hypotensive drugs on the regulation of the blood pressure, especially in orthostatism. They review the hypotensions induced by anti-hypertensive drugs, psychotropes, anti-Parkinson drugs, vasodilators and they classify these drugs following the risk of hypotension.They discuss the clinical diagnosis of orthostatic hypotension. Finally they present the anti-hypotensive drugs and suggest a programme of therapy depending on etiology of the hypotension.