Indapamide is a thiazide-related diuretic drug with antihypertensive properties. Its blood pressure-lowering action has been repeatedly demonstrated in acute as well as chronic conditions in various genetically and nongenetically determined forms of hypertension. In rats, the maximally effective oral dose is 3 mg/kg/24 h. The natriuretic effect of indapamide peaked at 3-fold at a dose of 1 mg/kg. In accordance with its antihypertensive properties, indapamide was shown to have excellent efficacy in protecting against target organ damage (heart, kidneys, brain). In addition to its natriuretic effect, it has been shown in several experiments that indapamide lowers the response to sympathetic nerve stimulation, exhibits calcium antagonist properties, enhances the production of prostacyclin, and limits the production of free radicals and of endothelium-dependent vasoconstrictor substances. These effects, even though they are observed at high indapamide concentrations and in a possibly species-dependent manner, may contribute to the beneficial properties of indapamide. The most recent data suggest that low doses of indapamide exert synergistic effects in combination with other antihypertensive drugs such as ACE inhibitors, the effects of which are influenced by the sodium status of the organism.