SummaryNumerous diuretic drugs are now available. They can be divided into three major groups: thiazids and analogs, diuretics of the Henle loop, and potassium sparing diuretics. Each group is characterized by specific properties as far as the diuretic effect and the clinical use concern. Thiazids are largely used in chronic management of cardiac failure and hypertension. Diuretics of the Henle loop are the first choice drugs in acute cardiac failure and in patients with renal failure. The use of potassium sparing diuretics, in our opinion, should be limited to clinical situation where potassium depletion has to be avoided.